Watch Servicing
& Repair

This handbook is a practical workflow for servicing wristwatches: identifying the movement, opening the case, stripping, cleaning, lubricating, reassembling and timing it, then closing it so that it keeps water out. For general horology (gearing, pivots, the history of escapements) see the hub's Clock Repair & Horology handbook. Here the focus is on what is particular to watches: smaller parts, tighter tolerances, a balance beating several times a second, and a case that has to seal.

1.1 Three Kinds of Movement

• Mechanical hand-wound: a mainspring wound by the crown, released through a train of wheels and regulated by an escapement and balance. Examples: ETA 6497 and 6498, descendants of the old Unitas pocket watch calibres.
• Automatic: the same, plus a weighted rotor that winds the spring as the wrist moves. Most can also be wound by the crown. Examples: ETA 2824-2, Seiko NH35, Miyota 8215.
• Quartz: a battery-powered circuit counts the vibrations of a quartz crystal at 32,768 Hz and pulses a small stepping motor that turns the hands. No balance, no mainspring, very little to lubricate.

1.2 Power: Mainspring, Barrel and Going Train

The mainspring is coiled inside the barrel, a toothed drum. Its inner end hooks onto the barrel arbor, its outer end onto the barrel wall. Winding turns the arbor; the spring then pulls the barrel round and the barrel drives the going train: centre wheel (once per hour), third wheel, fourth wheel (once per minute) and escape wheel. The 2824-2's component list names its train as intermediate wheel, third wheel, second wheel and escape wheel, an indirect centre-seconds layout.

Each stage raises speed and divides torque, so very little energy reaches the escape wheel. That is why a speck of dirt or dried oil near the escapement can stop a watch that would shrug off the same fault near the barrel.

1.3 Keyless Works: Winding and Setting

The keyless works let one crown both wind and set. ETA's names for the parts are winding stem, winding pinion, sliding pinion (the clutch), yoke, setting lever, setting lever jumper, setting wheel, crown wheel and ratchet wheel, with the click holding the ratchet.

The winding pinion turns freely on a round part of the stem; the sliding pinion has a square hole and always turns with the crown. In the winding position the yoke holds the sliding pinion against the winding pinion, which drives the crown wheel and the ratchet wheel on the barrel arbor. Wound backwards, the ratchet-shaped teeth slip, which is the clicking you feel.

Pull the crown out and the setting lever, whose pin sits in a groove on the stem, swings the yoke; the sliding pinion moves inwards to mesh with the setting wheel, which drives the minute wheel and the hands. Many calibres, the 2824-2 among them, also have a stop lever that touches the balance when the crown is fully out (hacking). Most crown faults are keyless faults: a worn sliding pinion, a weak setting lever jumper, or a stem cut too long. The setting lever is also what holds the stem in, which is why stem removal (Section 4.2) starts there.

1.4 Motion Works

Under the dial, the cannon pinion carries the minute hand and drives the minute wheel, whose pinion drives the hour wheel at one twelfth the speed. The cannon pinion is held by friction: the train drives the hands through it, and it slips when you set the time. Too little friction and the hands slip; too much and setting is stiff. On the 2824-2, ETA's chart greases this friction point (Moebius 9501 or Jismaa 124 in the 2009 document, Moebius 9504 in later editions). Check the chart rather than assuming.

1.5 The Swiss Lever Escapement

The escapement lets the train advance in small equal steps and gives the balance a push on every swing. Almost every mechanical wristwatch uses the Swiss lever. The clock handbook's section on the watch lever escapement covers lock, draw, drop and overbanking; here are the parts you will handle.

• Escape wheel: a light steel wheel with club-shaped teeth.
• Pallet fork: a lever on the pallet staff carrying two ruby pallet stones (entry and exit), set in slots with shellac.
• Horns, notch and guard pin: the forked end of the lever receives the impulse jewel; the guard pin under the notch meets the safety roller and stops the lever flipping across if the watch is knocked.
• Banking: pins or solid faces that limit the lever's swing.
• Impulse jewel: a ruby pin in the impulse roller on the balance staff, also usually set in shellac.

The balance swings freely. As it passes its centre point, the impulse jewel enters the notch and moves the lever, unlocking an escape wheel tooth. The tooth slides across the stone's impulse face, pushing the lever and so the balance, then drops onto the other stone and locks. Draw holds the lever against its banking until the balance returns. Each lock is one tick, or beat.

1.6 Balance, Hairspring and Regulator

The balance is a weighted wheel on a staff; the hairspring is the fine spiral that makes it oscillate. Its inner end is pinned to a collet on the staff and its outer end to a stud in the balance cock. A flat hairspring, as in the 2824-2 and NH35, is cheap and robust but breathes slightly off-centre. A Breguet overcoil, with its outer coil raised and curved inwards, breathes more concentrically and usually performs better in different positions; it is found mainly in higher-grade movements and is much harder to handle.

Most movements regulate with a regulator (index) carrying two pins either side of the outer coil. Moving it towards + shortens the effective spring and the watch gains.

• Simple index: a lever against a + / − scale.
• Swan-neck or micrometer: an adjusting screw for very fine control.
• Etachron: listed in the 2824-2 component list as an Etachron regulator and stud support. The stud support can be turned in the balance cock, so the beat can be adjusted with the movement running.
• Free-sprung: no regulator pins; rate is set by weights on the balance rim. Leave these to a professional unless trained.

1.7 Jewels, Endstones and Shock Protection

Watch jewels are synthetic ruby: hard, smooth bearings that wear slowly and hold a drop of oil in their oil sink. A hole jewel is pierced for the pivot; a cap jewel (endstone) sits against the pivot's end and holds a tiny reservoir of oil. The jewel count reflects construction: higher counts add bearings for the train and, in automatics, the winding wheels. The 2824-2 has 25 and the NH35A 24.

Balance pivots are often under a tenth of a millimetre across. A shock absorber mounts the balance jewels in a sprung setting, so under a knock the setting moves and the staff's stronger section takes the load. Incabloc is recognisable by its lyre-shaped spring; KIF and makers' own systems (Miyota uses Parashock) work on the same principle.

1.8 Automatic Winding

An automatic adds a rotor on a ball or plain bearing. A reversing mechanism turns its two-way swing into one-way winding: ETA uses two reversing wheels with internal clicks (the 2824-2 lists a reversing wheel and an auxiliary reversing wheel); Seiko uses its Magic Lever, a pawl lever driven by an eccentric. A reduction train then drives the ratchet wheel.

To prevent overwinding, automatics use a slipping (bridle) mainspring: a separate strip at the spring's outer end presses against the barrel wall and slips round it when the spring is fully wound. ETA calls the part a "mainspring with sliding attachment". A braking grease on the barrel wall sets the slipping torque (Section 6.2).

1.9 Inside a Quartz Watch

An analogue quartz movement has a tuning-fork quartz crystal at 32,768 Hz (2¹⁵), an integrated circuit that divides this down and drives a stepping motor (coil, stator and magnetised rotor), and a gear train to the hands. ETA's document for its 955.112, for example, gives a current consumption of about 1.2 µA, a coil resistance of 1.30–1.80 kΩ, and an end-of-life indication in which the seconds hand jumps 4 steps every 4 seconds below 1.30 V. Chapter 8 covers quartz service.

You cannot order a part, find a lubrication chart or set up a timegrapher until you know exactly which calibre you have. Identify the movement first, ideally before you buy a watch to work on: some calibres have plentiful parts and documents, others have none.

2.1 What the Markings Tell You

• Maker and calibre number: such as "ETA 2824-2" or "SEIKO NH35A", usually under the balance or rotor or on a bridge. Brands often rename bought-in movements; the base calibre is what matters for parts.
• Jewel count: "25 JEWELS", often on the rotor. Useful for telling variants apart.
• Origin and grade: "Swiss Made", "Unadjusted" (not adjusted for position or temperature, which does not mean poor), "Adjusted to x positions".
• Size in lignes ('''): an old French unit of about 2.256 mm. ETA gives the 2824-2 as 11½''' (25.60 mm) and the 6497/6498 as 16½''' (36.60 mm).

If the back of the movement is anonymous, look at the dial side of the main plate once the dial is off (Section 4.4). Numbers are often stamped there, and the keyless and calendar layout is distinctive.

2.2 A Step-by-Step Identification Method

The best known free reference is the Ranfft archive (ranfft.org), a database of calibres with photographs, sizes, jewel counts and beat rates. Supplier catalogues and collectors' forums are the other main sources.

1. Photograph the movement square on, both sides if possible, and read every marking under a loupe.
2. Measure the diameter with a caliper; divide by 2.256 for lignes.
3. Note the features: hand-wound or automatic, date or day-date, centre or small seconds, hacking.
4. Count the beat on a timegrapher or phone app, or against a stopwatch: 8 ticks a second is 28,800 vph, 6 is 21,600, 5 is 18,000.
5. Compare bridge shapes and screw positions with reference photographs; they are the most reliable visual identifiers.
6. Confirm with the maker's technical document. ETA, Seiko (through its TMI movement business) and Citizen's Miyota division publish specifications and, for many calibres, service documents.

2.3 Common Calibres and Their Specifications

Data from the makers' current technical documents and product pages. ETA now quotes both a minimum and a typical power reserve. Lift angle is needed for timegrapher set-up (Section 7.2).

2.4 Beat Rates Explained

Beat rate is given in vibrations (beats) per hour, written vph or A/h. One beat is a single swing of the balance; a full oscillation is two beats.

A higher beat resists disturbance better and sweeps more smoothly, at the cost of faster wear. In practice, the timegrapher must be set to the right beat rate or its readings are meaningless.

Watch work needs a handful of good tools kept in perfect condition, and a clean, well-lit place to use them. The clock handbook's workspace and hand tools sections apply; what follows is specific to watches.

3.1 The Bench and the Room

• Height and support: a bench higher than a desk lets you sit upright with forearms supported.
• Surface and floor: a smooth, pale, non-shedding surface with a lip or tray, and a hard floor or a pale sheet under the chair. A part dropped on carpet is usually gone.
• Light: bright, even, cool-white light with no hard shadows.
• Dust: cover parts between sessions, keep trays lidded, use a rubber bulb blower (not canned air), and do final assembly in one sitting if you can.
• Magnetism: keep phones, tablets, speakers and magnetic holders off the bench, choose anti-magnetic tweezers, and check screwdrivers with a compass. A magnetised hairspring is a common cause of a watch suddenly running hundreds of seconds fast (Section 7.7).

3.2 Screwdrivers and Tweezers

Buy a screwdriver set with graded, replaceable blades and swivel heads. The blade must fill the slot in width and fit snugly in thickness; a loose blade burrs the head, and a burred blued screw cannot be made new. Dress blades on a fine stone so the tip is flat, square and parallel-sided for its last fraction of a millimetre, and check them under the loupe before every service.

Tweezers are the watchmaker's fingers. You need a fine anti-magnetic pair (often No. 5) for small parts, a stronger pair (No. 2 or 3) for bridges, and a brass or plastic pair for dials, hands and batteries. The tips must meet exactly without crossing; badly dressed tweezers are the main cause of parts flying across the room.

3.3 Holding the Movement and Opening the Case

A movement holder clamps the movement by its edge. Universal holders fit most sizes; inexpensive dedicated holders for common calibres such as the 2824-2 and NH35 support them better.

• Case knife: for snap-on backs. Use the lifting notch and twist rather than lever.
• Case back wrench: the three-jaw adjustable type (often called a Jaxa wrench) for notched screw backs. Jaws must fit the notches exactly and sit square.
• Friction ball: a rubber ball for shallow-notched screw backs; leaves no marks.
• Case press: with nylon dies, for snap-on backs, crystals and bezels. Never press a back on by hand or in a vice.
• Case holder: grips the watch while you work; protect polished sides with plastic jaws or tape.

3.4 Hands, Crystals and Presses

• Hand levers: a pair of flat levers that lift the hands straight up. Use a thin plastic dial protector under them.
• Hand-setting tool: plungers that press hands on squarely down the pipe.
• Crystal press and crystal lift: for pressed-in crystals, and a claw that contracts acrylic tension crystals.

3.5 Oilers, Lubricants and Rodico

Oilers are fine wires with a flattened tip that carry a measured drop; three or four sizes cover most work. A covered oil pot keeps each lubricant separate and clean. Decant only a few drops at a time and renew them regularly, because oil ages in the pot as well as in the watch. Chapter 6 explains which lubricant goes where.

Rodico is a soft cleaning putty for lifting dirt and fingerprints and cleaning oiler and tweezer tips. Keep it away from fresh oil and off the balance. Wear finger cots or nitrile gloves when handling cleaned parts: skin oils mark plates and start corrosion.

3.6 Magnification

A practical loupe set is 3× or 4× for case work, 5× or 6× for movement work and 10× for inspecting pivots, jewels and pallet stones. A stereo microscope at roughly 7× to 20× with a long working distance transforms the work: depth perception makes oiling and hairspring work much easier. It is the single biggest upgrade if you service more than the occasional watch.

3.7 Timegrapher and Demagnetiser

A timegrapher listens to the watch through a microphone stand and shows rate (seconds per day), amplitude (degrees) and beat error (milliseconds), with a trace. Affordable bench units are widely sold. Phone apps are useful for a quick check but less reliable for amplitude. A demagnetiser is an AC coil that scrambles magnetism as the part is withdrawn with the field on (Section 7.7).

3.8 A Sensible Starter Kit

Start with: a dressed screwdriver set; two or three pairs of tweezers including plastic; a movement holder for your practice calibre; case knife, three-jaw wrench and case holder; hand levers, dial protector and hand-setting tool; loupes; three or four oilers and an oil pot; the lubricants your calibre's chart calls for; Rodico, pegwood, finger cots and a blower; and a lidded, compartmented parts tray. Add a press, timegrapher and demagnetiser as soon as you can: the timegrapher is the most useful single diagnostic tool you will own.

More watches are damaged getting into and out of the case than in the movement. Protect every polished surface, and remember that a case will only seal again if its seals are treated properly. Before opening anything, photograph the watch and note existing marks.

4.1 Opening the Case Back

If a screw back will not move: check the case is firm in its holder and the jaws are square and fully engaged (most slips come from a jaw riding on the edge of a notch); try firm downward pressure as you turn; try a friction ball. If it still will not move, stop. Backs can be cross-threaded or corroded in, and a professional's bench-mounted opener holds case and tool rigidly. Forcing it risks a gouged back and a cracked crystal.

4.2 Removing the Crown and Stem

The setting lever holds the stem in the movement. To release it you press a setting lever screw or release push-piece while drawing the crown gently out.

1. Unscrew a screw-down crown fully, then pull the crown to the setting position; on many calibres the release only works there.
2. Find the release. On the 2824-2 and many Swiss calibres it is a small point or screw head beside the stem, sometimes marked with an arrow. On the NH35 it is a small push-piece beside the stem on the back of the movement. The technical document shows it.
3. Press it gently with a fine screwdriver or pegwood and pull the crown out. Press too hard, or turn a screw type too far, and the setting lever can drop out of place inside the movement, which means taking the dial off to refit it.
4. To refit, press the release again (or on some calibres simply push the stem home) until it clicks, and check every crown position.

A new stem must be cut to length: a little long at first, then down gradually until the crown sits correctly against the tube in every position.

4.3 Taking Out the Movement

Movements are held by case clamps (loosen the screws a turn and rotate them clear), a movement ring filling the gap between movement and case, or screws, often in combination. With the stem out and clamps loosened, cover the movement with a soft cloth, turn the case over onto a cushion, and let the movement drop out dial-down. If it must come out through the back, lift it by its ring, never by the rotor or balance, and never let the hands touch anything.

4.4 Hands and Dial

1. Note the exact hand position at which the date changes on a calendar watch.
2. With the movement in a holder, lay a dial protector (thin plastic with a slot to the centre) over the dial.
3. Place the hand levers either side of the hand stack under the hour hand pipe and press straight down evenly. Keep the hands in a covered tray; do not grip luminous hands by the lume.
4. Dials are held by dial feet gripped by dial foot screws (often eccentric, so loosen only a part turn), by clamps, or on many modern calibres, including Seiko and Miyota automatics, by adhesive dial dots. Lift the dial by its edges. Never prise under it with a blade.

Refitting: fit the hour hand at the position where the date has just changed (usually 12), pressing it on squarely with the hand-setting tool; then the minute hand at 12 and the seconds hand at 12. Check from the side that the hands are parallel with clearance between them, then turn them through 24 hours watching every crossing point.

4.5 Crystals: Acrylic, Mineral and Sapphire

The reliable way to identify a crystal is the maker's specification for the case reference; mineral glass and sapphire can be hard to tell apart by eye. Measure diameter to a tenth of a millimetre and note thickness and shape before ordering. Always remove the movement first. Fit a new gasket of the right size, and press the crystal in slowly and squarely with flat dies bearing on its edge.

4.6 Gaskets and Seals

A water-resistant case seals at the back, the crown and the crystal (plus push-pieces and valves where fitted).

• Case back gasket: an O-ring or flat gasket. Replace it at every service; old gaskets take a set and crack.
• Crown seal: O-rings inside the crown that seal on the tube. The commonest leak path, because the crown moves.
• Crystal gasket: replace whenever the crystal comes out.

Match gaskets by inside diameter, outside diameter and section; boxed assortments are sold by material suppliers. Grease O-rings very lightly with silicone grease sold for watch gaskets so they seat without twisting or being cut, and wipe off any excess.

4.7 What Water Resistance Ratings Mean

ISO 22810:2010 (which replaced ISO 2281:1990) covers watches described as water-resistant. Its tests include immersion at a minimum overpressure of 2 bar for 10 minutes (manufacturers may specify and mark higher values), immersion at 10 cm for at least an hour, 5 minutes at 10 cm with a force of 5 N on the crown and push-pieces, and a thermal shock of 5 minutes each at 40 °C, 20 °C and 40 °C. Each is checked with a condensation test: the watch is warmed on a plate at 40–45 °C, a drop of water or a wet cloth at 18–25 °C is put on the crystal, and after about a minute there must be no condensation inside.

So the depth or pressure on a water-resistant watch is a test pressure, not a recommended diving depth. Swimming and showers create dynamic pressures and seals age. The standard leaves it to the manufacturer to say which activities a watch suits, so check its instructions.

ISO 6425:2018 covers divers' watches. It applies to watches designed for diving to at least 100 m, with a diving time indicator (such as a rotating bezel) protected against accidental operation, readable to one minute over at least 60 minutes and legible in the dark. Its tests include magnetic resistance to ISO 764, temperature cycling, a 48-hour salt spray, shock resistance to ISO 1413, 48 hours' immersion at 30 cm with the controls operated, and an overpressure of 125 per cent of the rated depth (Δp = (L + 0.25 L)/10 bar) with 5 N on the crown and push-pieces. Every production watch must also pass a water overpressure test.

4.8 Pressure and Condensation Testing

• Dry (air) testers measure the tiny deflection of the case under air pressure or vacuum. A leaking watch shows no lasting deflection. No water is involved, so this is the usual first test.
• Wet testers pressurise the watch under water, then release the pressure and look for bubbles from the leak. They locate a leak but let water in if there is one, so they normally follow a passed dry test.

At home, the condensation test above will show a watch that has already let moisture in, though it cannot prove water resistance. Without a tester, have a jeweller or watch repairer test the cased watch.

This chapter and the next follow a full service of the ETA 2824-2, chosen because it is common, well documented and widely copied. The sequence applies, with layout changes, to most automatics. Read both chapters first and keep the calibre's technical document open beside you.

5.1 Before You Start

1. Time it first. Wind fully and record rate, amplitude and beat error dial up and crown down (Chapter 7). This is your diagnosis and the baseline to beat.
2. Check the functions: hand and rotor winding, setting, date change, quick-set, hacking.
3. Prepare a clean bench, a lidded compartment tray, fresh oil in a clean pot, dressed tools and finger cots.
4. Photograph each stage, especially screw positions and the keyless and calendar layout. Screws that look alike often differ in length, and a long screw in a short hole can crack a jewel.

5.2 Letting Down the Power

Never dismantle a movement with power in the mainspring. Remove the pallet fork under power and the train spins uncontrolled, stripping teeth and breaking pivots; remove the barrel bridge under power and the click and ratchet can fly.

On the 2824-2, take the automatic device off first (Section 5.3) to expose the ratchet wheel and click. Then hold the crown firmly, wind a fraction of a turn to take the pressure off the click, hold the click clear with pegwood, and let the crown turn back slowly through your fingers until the spring is down. Alternatively, let the watch run down fully before you start. Either way, check that the balance will not restart when given a gentle swirl. The clock handbook covers letting down a clock mainspring, where far more energy is involved.

5.3 Disassembly Order for an ETA 2824-2 Type

ETA's document lists parts in assembly order; disassembly is the reverse. Part names are ETA's.

Rotor Side

1. Automatic device: undo the framework screws and lift it off with the rotor. Then let down the power (5.2).
2. Balance: remove the balance bridge screw and lift the bridge with the balance hanging from it by the stud. Rest it upside down on a cushion under a cover. Never let the balance dangle, and never touch the hairspring.
3. Pallet fork: remove the pallet bridge and lift the fork by its body, not the stones.
4. Ratchet wheel, crown wheel, click and click spring. Some crown wheel screws have a left-hand thread; check the document before forcing one. Note how the click spring sits.
5. Barrel bridge and barrel, then the train wheel bridge (lift it straight up) and the second, third, escape and intermediate wheels.

Dial Side

1. Hands and dial (Section 4.4).
2. Calendar: date indicator, date jumper and its plate, driving wheel, correctors. Photograph first; the jumper is under spring tension.
3. Motion works: hour wheel, minute wheel, and the cannon pinion with driving wheel, lifted straight off the centre tube.
4. Keyless works: setting lever jumper (finger over the spring), setting wheel, setting lever, yoke, sliding and winding pinions.
5. Shock settings and cap jewels, if cleaning them separately.

5.4 Inspection

Inspect every part under magnification before cleaning, to see the pattern of wear and old oil, and again afterwards.

Check endshake and sideshake too: with the train assembled and unpowered, each wheel needs a small, free vertical and slight sideways play. None means a bent bridge or misfitted part; too much means wear. The clock handbook's section on assessing wear explains the principles.

5.5 Machine Cleaning

A watch cleaning machine spins a compartmented basket of parts through a cleaning solution, two or more rinses and a heated drying chamber; most now add ultrasonic agitation. Load plates, bridges, wheels, keyless and calendar parts, screws in fine mesh, but keep the balance and pallet fork out (5.6). Use only solutions made for watch cleaning machines, run the cycle their maker recommends, and change them on schedule. Unload under a cover, peg any jewel holes that still show residue, and inspect. The clock handbook describes rotary machine cleaning in more detail.

5.6 Hand Cleaning and What to Keep Out

A good service is possible without a machine. Use three small lidded jars, one of watch cleaning solution and two of rinse; brush each part in the cleaner, pass it through both rinses, and dry it on clean tissue or with warm air. Then:

• Peg every jewel hole: twist a sharpened pegwood point into it from both sides, repeating with fresh points until it comes out clean. This is the most effective single step of a hand clean.
• Clean cap and hole jewels separately. Dried oil between them is a common cause of low amplitude.
• Balance and pallet fork: a brief dip in a non-alcohol rinse, moved gently, then dried. Do not brush the hairspring.

Before reassembly, pass a small compass near the balance, pallet fork, escape wheel and tweezers. If the needle moves, demagnetise (Section 7.7).

5.7 Epilame Treatment

An epilame lowers the surface energy of a part so that oil stays where it is placed instead of spreading away and leaving the bearing dry. The usual product is Moebius Fixodrop. Moebius describes the current Fixodrop ES as a fluorinated polymer in a partially fluorinated solvent, leaving an invisible film a few nanometres thick; its ready-to-use ES/BS-10 (8981) is for metals and rubies. ETA's current 2824-2 document says: "After washing and before reassembly, coat with the Moebius Fixodrop ES/BS 8981 epilame", with ES/WR-S 7061 and ES/WR-P 7071 also permitted.

1. Parts must be clean and dry. Moebius says all parts in contact with a lubricant should be treated; follow your calibre's document.
2. Dip with stirring for at least 30 seconds, drain by spinning, and dry with warm air (Moebius suggests about 60 °C, which also prevents condensation marks in humid conditions).
3. Close the bottle at once; the solvent is very volatile.
4. Moebius advises letting the movement run for a few minutes before lubricating the escapement's pallet stones (Section 6.4).

Moebius states the film resists ordinary cleaning agents and is removed by polishing or strong alkaline soap.

Clean parts assembled dry wear quickly; parts flooded with oil gather dirt and stop. The aim is the right lubricant, in the right place, in the right quantity.

6.1 The Lubricants and What Each Does

Lubricants are specified by the movement maker. The table lists the Moebius products named in the ETA documents used here, with Moebius's descriptions. It matches the hub's clock lubrication reference: 9010 is the watch oil for fine pivots and balance jewels, 9415 the pallet grease and 941 the pallet oil, D5 (now HP-1300) the heavier oil for barrel arbors and motion work, and 8200 the mainspring grease.

6.2 Mainspring and Barrel

Hand-wound: the spring's outer end hooks into the barrel wall. Remove the barrel lid, lift out the arbor, and take the spring out with a mainspring winder, which winds it into a sleeve without distortion; pulled out by hand, a watch spring distorts permanently (see the clock handbook on mainspring winders). Replace a spring that has lost most of its curve out of the barrel, or is rusty, kinked or cracked, with the specified size (height, thickness, length, end type). Many replacements come wound into a ring that pushes straight into the barrel. Lubricate as charted: typically a thin film of mainspring grease such as 8200 on the coils and the specified oil on the arbor.

Automatic: the bridle needs braking grease on the barrel wall, such as Moebius 8217, as a very thin film where the bridle bears. Too little and it slips early, cutting power reserve and amplitude; too much and it may not slip. Do not put braking grease on the coils. ETA's 2824-2 component list gives the "movement barrel complete" as one part, and many watchmakers fit a new complete barrel at each service of a production movement. If a barrel is supplied complete, follow the maker's instructions rather than opening it.

6.3 Reassembly Order

ETA's assembly list for the 2824-2 basic movement runs: main plate, lower balance shock absorber, intermediate wheel, escape wheel, third wheel, second wheel, train wheel bridge, barrel, barrel bridge, crown wheel parts, click and spring, ratchet wheel, pallet fork, pallet bridge, regulator and upper shock absorber, balance with balance bridge; the automatic device goes on last. In practice:

1. Keyless works on the dial side first, lubricated as charted. Check the stem clicks positively through each position.
2. Train: fit the wheels, oil the lower jewels, lower the train wheel bridge and guide each pivot into its jewel before tightening any screw. If the bridge will not sit flat under its own weight, a pivot is out. Never screw a bridge down onto a pivot.
3. Check freedom: a puff from the blower should set the whole train spinning and coasting to a stop. An abrupt stop means something binds.
4. Barrel, barrel bridge, crown wheel, click, ratchet wheel. Wind a turn or two and watch the train run evenly.
5. Pallet fork and bridge. Nudged with pegwood, the fork should snap crisply between bankings and the wheel advance one tooth each time. Then lubricate the pallet stones (6.4).
6. Balance: lower balance and cock together, guiding the impulse jewel into the notch. The balance should start by itself or with a tiny swirl. Tighten the screw only when the cock sits flat. Oil the cap jewels and refit the shock springs.
7. Time the bare movement (Chapter 7); problems are far easier to fix now.
8. Dial side: motion works, calendar, dial, hands. Then the automatic device, and retime.

6.4 The Lubrication Map

Each calibre's document marks every lubrication point with a symbol. The summary follows the logic of ETA's 2824-2 charts; use it to read the chart, not instead of it.

Pallet Stones

This is the most critical point in the movement. With the fork fitted and a little power on, but the balance not yet in: pick up a tiny amount of 9415 on the finest oiler and touch it onto the exit stone's impulse face as a tooth rests on it. Move the fork with pegwood to let several teeth pass, and repeat at intervals round a full turn of the escape wheel; many watchmakers lubricate about every third tooth. Under high magnification you want a thin, even film on the impulse faces, not a blob.

6.5 How Much Oil

Follow any quantity marks the maker gives (Seiko distinguishes "normal" and "sufficient" quantity; ETA marks "very small quantity" at some points). Otherwise, as general workshop practice:

• Jewel holes: oil into the sink, forming a small ring around the pivot about half filling it, never spreading onto the plate.
• Cap jewels: a drop roughly half the jewel's diameter on its centre before fitting; capillary action draws it around the pivot tip.
• Greases: a thin film, never a lump.
• If in doubt, less. Oil that migrates onto the hairspring makes coils stick, and the watch can gain hundreds of seconds a day.

The clock handbook's How Much Lubrication explains the effects of too much and too little.

6.6 Servicing the Automatic Module

The 2824-2's automatic device carries the reduction wheel, a ratchet wheel driving wheel, two reversing wheels and the rotor on its ball bearing. Check the bearing turns smoothly and quietly without noticeable play: a worn one lets the rotor scrape the case back. Check each reversing wheel turns freely one way and locks the other. Worn reversers are a frequent cause of a watch that winds by hand but not by rotor, and they are inexpensive to replace. Clean, reassemble, lubricate as charted, and check that the rotor winds in both directions and coasts freely. On Seiko calibres, the Magic Lever and its pawls are a known wear point on older, high-mileage watches, and a replacement lever is inexpensive.

6.7 Seiko and Other Makers' Own Charts

Seiko's NH3 series (NH34A to NH39A) technical guide marks each oiling point with either Moebius 9010 or Seiko's own oils, designated S-6 and S-4 in the current guide (an earlier NH3 parts sheet names MO-3 and MO-4), with separate quantity marks. Miyota's product page for the 8215 lists AO oil and AO grease. If you cannot obtain a maker's lubricant, use the closest Moebius equivalent for the job and record what you used, aware that you are departing from the specification.

A timegrapher turns a watch's tick into numbers. Used well, it diagnoses faults before you open the case and proves your service afterwards. The clock handbook introduces the timing machine; this chapter goes further for watches.

7.1 What a Timegrapher Measures

Each tick of a lever escapement is a cluster of sounds: unlocking, impulse, and the drop onto the locking face. The timegrapher times these and successive ticks.

7.2 Lift Angle and Why It Matters

The timegrapher cannot see the balance. It infers amplitude from how long the impulse jewel takes to pass through the fork, the arc called the lift angle. The faster the balance passes, the larger its amplitude. Set the lift angle wrongly and rate and beat error are unaffected, but amplitude is wrong: too large a setting reads too high. Do not assume your machine's starting value suits your watch. ETA gives 50° for the 2824-2, 51° for the 2892-A2, 49° for the 7750 and 44° for the 6497-1 and 6498-1; Seiko gives 53° for the NH3 series (Appendix A).

7.3 Reading the Trace

• A, healthy: two level lines close together.
• B and C, gaining or losing: sloping lines; adjust rate (7.6).
• D, beat error: lines well apart; adjust beat (7.5).
• E, periodic wave: usually a fault in one wheel (bent pivot, damaged tooth, out-of-round wheel). Time the period to find which: once per escape wheel turn points to the escape wheel, a longer period to the fourth wheel, and so on.
• F, erratic: check the microphone clamp first, then suspect dirt, a hairspring touching, a damaged stone or magnetism.

7.4 Positional Testing

Standard positions are dial up (DU), dial down (DD), and the four verticals crown up, down, left and right (CU, CD, CL, CR). Seiko's NH3 guide uses clock-face names: accuracy dial up, 9 up and 6 up, and positional difference in the 12, 9, 6 and 3 up positions, measured 10 to 60 minutes after full winding, 20 seconds per measurement. A practical routine: wind fully, let it settle, record all six positions, then repeat dial up and one vertical after 24 hours unwound to see how it behaves as the spring runs down.

Makers publish their own tolerances; Seiko's −20 to +40 s/d for the NH35A is typical of an everyday automatic. As general workshop guidance, not a published standard, a clean, healthy Swiss lever movement at full wind usually shows about 270–300° dial up and somewhat less vertically. Below roughly 220–230° dial up at full wind, or a large horizontal-to-vertical drop, points to dirt, dried oil, wear, a weak spring or an escapement fault. Very high amplitude risks knocking (overbanking): a sudden gallop and a wildly gaining rate.

7.5 Adjusting Beat Error

Beat error is corrected by turning the stud (or collet) relative to the balance so its rest position lines up with the fork. Many watchmakers aim for under about 0.5 ms on an everyday watch. With an adjustable stud carrier (Etachron and similar), move it a tiny amount with the watch running on the timegrapher and let the reading settle. With a fixed stud, the balance must come out and the collet be turned on the staff by trial and error, a delicate job to practise on a scrap balance. Adjust beat before rate, because moving the stud carrier can shift the regulator.

7.6 Adjusting Rate

Fully wound, read the rate in a representative position (or the average of dial up and one or two verticals). Move the regulator a very small amount towards + or −, or turn the micrometer screw, and let it settle. A watch on the wrist runs warmer and through every position, so aim for a small bench gain and check against a reliable time reference over several days of wear.

7.7 Magnetism and Demagnetising

Steel hairsprings are easily magnetised by phone cases, laptop lids, speakers and magnetic clasps. The coils then stick together, and the watch typically gains heavily, often hundreds of seconds a day, with a ragged trace. Seiko's manual for its 7S26-based divers' watches quotes a magnetic resistance of 4,800 A/m (60 gauss), the level ISO 764 sets for magnetic-resistant watches.

1. Pass a small compass slowly around the watch; a deflecting needle shows magnetism.
2. Put the watch on the demagnetiser, press and hold the button, and draw the watch slowly away to arm's length before releasing. Releasing it on the coil can leave it more magnetised.
3. Repeat, turning the watch 90°, then recheck with compass and timegrapher. Demagnetise your tweezers and screwdrivers too.

Quartz watches are simpler than mechanical ones, but a careless battery change is still the commonest way they are damaged. The clock handbook's quartz fault-finding follows the same logic for larger movements.

8.1 How an Analogue Quartz Watch Works

The circuit drives the crystal at 32,768 Hz, divides by two fifteen times to get one pulse a second, and sends alternating pulses to the motor coil; each flips the rotor half a turn. Average current is tiny: about 1.2 µA for the ETA 955.112. Many movements have an end-of-life (EOL) indicator; on the 955.112 the seconds hand jumps 4 steps every 4 seconds below 1.30 V, so a "jumping" seconds hand usually means a low battery, not a fault. Many also stop the motor when the crown is pulled out (ETA tests this state at about 0.5 µA).

8.2 Batteries: SR, LR, SW and W

• SR cells are silver oxide, 1.55 V nominal. Maxell describes their voltage as high and flat until the end of discharge: what analogue quartz movements are designed for.
• LR cells are alkaline, 1.5 V, in the same sizes. Maxell notes their voltage slopes through discharge and their energy density is lower. They may run a watch, but for less time; use silver oxide.
• Size code: the leading digits stand for the diameter rounded down to whole millimetres (6 for 6.8 mm, 9 for 9.5 mm, 11 for 11.6 mm), the last two for the height in tenths of a millimetre. An SR626 is 6.8 × 2.6 mm.
• SW and W: Maxell describes SW as the long-life low-drain type for analogue watches and W as the high-drain type for multifunction digital watches with lights and alarms. Renata's 371 is SR920SW and its 370 is SR920W: same size, two types.
• CR cells are 3 V lithium and not interchangeable with 1.55 V cells.

8.3 Changing a Battery Properly

1. Open the case (4.1) and identify the cell from the old one, the movement marking or its document, including SW or W.
2. Release the battery clamp without levering against the circuit or coil, and lift the cell out with plastic tweezers. Metal tweezers across a cell short it, and can damage the circuit.
3. Clean light tarnish from the contacts with a pencil eraser or a barely moistened cotton bud, kept off the dial. Green or white crystals mean a leak (8.5).
4. Fit the new cell the right way up (usually + up) and refit the clamp. Some movements need a reset by briefly linking a marked point (often AC) to the battery positive; do this only if the movement's document says so.
5. Watch a few steps of the seconds hand, fit a lightly greased new case back gasket, close, and test water resistance if the watch is rated for it (4.8).

8.4 Testing Coil and Circuit

Makers publish electrical test values. ETA's document for the 955.112 specifies tests at 20–25 °C including:

An open or near-zero coil reading means a damaged coil. A good coil with no output points to the circuit or crystal. Good coil and output but no hand movement means a mechanical fault. High consumption while running usually means drag in the train, which shortens battery life.

8.5 Common Quartz Faults and Service

• Leaked battery: light deposits clean off; heavy corrosion of the circuit usually means a new circuit block or movement.
• Dead after water ingress: usually a new movement.
• Losing time with a new battery: drag from old oil or debris making the motor miss steps; clean and lightly re-oil the train, or replace the movement.

Everyday quartz movements (from ETA, Ronda, Miyota and Seiko/TMI among others) are often replaced as modules, since a new one costs less than the labour to repair the old. Better quartz calibres are serviced like a small mechanical movement, oiled only at the points on the maker's chart. Never oil the motor rotor or crystal, and keep the coil and circuit out of cleaning solutions unless the maker says otherwise.

Work from the outside in: check simple external causes first and use the timegrapher before taking anything apart. Causes are listed in rough order of likelihood.

9.1 Stops or Will Not Start

9.2 Runs Fast or Slow

9.3 Low Amplitude

9.4 Winding and Setting Problems

9.5 Hands, Date and Calendar

9.6 Moisture, Fogging and Crown Issues

10.1 Spring Bars and Straps

Straps and bracelets attach to the lugs with spring bars: a tube with a spring inside and a shouldered pin at each end that locates in a hole in the lug. A spring bar tool has a fork at one end (to compress the bar from between the lug and the strap) and a pin at the other (to push through lug holes where the case has drilled lugs).

1. Turn the watch face down on a soft cloth. Cover the lugs with low-tack tape if they are polished.
2. Slide the fork between the strap and the lug, catch the shoulder of the spring bar, and compress it towards the centre. The end drops out of the lug hole; lift the strap away.
3. To refit, put one end of the bar in its lug hole, compress the other with the fork, and slide it along the lug until it snaps into the hole. Pull the strap firmly to check both ends are home.

Match spring bars to the lug width (measured inside the lugs) and the thickness the case needs, and replace any that are bent, rusty or weak: a failed spring bar is an easy way to lose a watch.

10.2 Bracelet Sizing

Metal bracelets are sized by removing or adding links. Links are held by one of:

• Pins: friction pins, split pins, or pin-and-collar systems. Push them out with a pin pusher in the direction of the arrows stamped on the inside of the link, if there are any. Support the bracelet in a holder so the pin has somewhere to go.
• Screws: screw-in bars. Use a screwdriver that fills the slot exactly. Some bracelets have screws at both ends of the bar; hold one end and turn the other.

Remove links equally either side of the clasp so it sits centrally under the wrist, and use the clasp's micro-adjustment holes for the final fit.

10.3 Case Refinishing

Cases have two common finishes: polished (mirror) surfaces and brushed (satin) surfaces with fine parallel lines. Many cases combine them, separated by sharp edges.

• Brushed surfaces can be refreshed with an abrasive pad or a fine abrasive stick drawn in the direction of the original grain, with the polished areas masked off with tape. Practise on scrap first.
• Polished surfaces can be cleaned up with a polishing cloth to remove light hairline scratches. Deeper scratches need machine polishing, which removes metal.

Remove the movement, crown, crystal and gaskets first, and clean out all compound afterwards.

10.4 Radium and Tritium Lume

Before about the 1960s many watches had luminous paint containing radium-226. It was then generally replaced by tritium, and from the 1990s onwards by non-radioactive photoluminescent pigments. If a vintage watch's lume is dark brown or black, cracked or crumbling and no longer glows after charging in light, suspect radium.

Radium

Radium-226 has a half-life of about 1,600 years, so old radium paint is still radioactive. The main risks are not from wearing a closed watch but from:

• Ingesting or inhaling paint particles. Radium is an alpha emitter, and alpha particles are dangerous inside the body. Old radium lume is often powdery and flakes off when a case is opened or hands are removed.
• Radon gas. Radium decays to radon, a radioactive gas, which builds up inside the case and in poorly ventilated storage. Researchers at the University of Northampton and Kingston University measured radon from a collection of 30 radium-dial military watches and found levels far above the UK's domestic radon action level of 200 Bq/m³ in a small room, with three deteriorated watches individually exceeding that level. Radon is the second leading cause of lung cancer in the UK after smoking.

Tritium

Tritium is a radioactive form of hydrogen with a half-life of about 12.3 years. It emits very low energy beta radiation that does not penetrate the crystal or case, and tritium lume from the 1960s to 1990s has now lost most of its activity, which is why it no longer glows. A small "T" printed beside "Swiss" at the bottom of the dial usually indicates tritium, although it is not proof. Old tritium lume is not considered the same hazard as radium, but it is fragile, and it is an important part of a vintage watch's originality and value, so treat it with the same care.

10.5 Originality and Value

On a collectable watch, originality matters as much as running. Original dials, even with patina, are usually worth far more than refinished or replacement dials, and relumed hands and dials reduce value. Correct period crowns, crystals and bezels are valued; a sharp, unpolished case is prized. Replacing a worn wheel with a correct new part is normal service; swapping the movement is not. Keep any parts you replace, labelled, return them to the owner, and record what was done.

10.6 Sourcing Parts in the UK

10.7 Service Intervals and When to Send It Away

There is no single correct interval. Many makers now recommend longer intervals for modern watches with synthetic oils and better seals, so check the maker's current advice. Regardless, have a watch serviced when its rate or amplitude has fallen noticeably, it stops or runs only in some positions, it has had a heavy knock or let in moisture, or winding and setting have become rough. Gaskets age whether or not the watch runs well, so have the seals of a watch worn in water checked periodically.

Send it to a professional for: any valuable watch until you have the skill on cheaper examples of the calibre; chronographs and other complications; free-sprung balances, overcoils and hairspring work beyond slight corrections; staff, jewel and pallet stone work, or anything needing a lathe; monocoque cases, stuck backs, crown tubes and dive-rating pressure tests; suspected radium lume; and watches under warranty, which opening may void.

These worked examples show the diagnostic and service process on three common jobs. They are illustrative composites of typical workshop cases, not records of particular watches, and the readings are typical of what you might see rather than measurements to aim for.

11.1 Servicing a Seiko NH35 (and the 7S26 Family)

11.2 Reviving a Low-Amplitude ETA 2824-2

11.3 A Quartz Watch That Won't Start

13.1 Lubrication Quick Map

Summarised from ETA's 2824-2 technical communications (2009 and 2022 editions) and Seiko's NH3 series technical guide. Always defer to the document for your calibre.

13.2 Timegrapher Reference

13.3 Service Checklist

1. Identify the calibre and obtain its technical document.
2. Timegrapher readings before opening: six positions at full wind, dial up and one vertical at 24 hours.
3. Note functions and faults. Photograph the watch.
4. Open case; remove stem, movement, hands, dial.
5. Let down power. Strip in order, photographing as you go.
6. Inspect every part before and after cleaning.
7. Clean; keep balance, pallet fork and finished parts out of the ultrasonic and alcohol. Peg jewels. Clean cap jewels separately.
8. Epilame if the document specifies it.
9. Replace worn parts, mainspring or complete barrel, gaskets.
10. Reassemble and lubricate to the chart: keyless, train (check freedom), barrel, pallet fork, pallet stones, balance.
11. Time the bare movement; set beat error, then rate.
12. Dial side: motion works, calendar, dial, hands. Check clearances and date change.
13. Automatic module; retime.
14. Case: new gaskets, crown seal, clean case. Close. Pressure test.
15. Run for several days and check rate and power reserve before returning.

Silver oxide watch cells from Renata's published product data and cross-reference guide. All are 1.55 V. Capacities are Renata's figures for its own cells; other makers' capacities differ slightly. "SW" is the low-drain type for analogue watches and "W" the high-drain type (Section 8.2).