A watch doesn't usually break. It wears out quietly, one small symptom at a time, and because none of those symptoms is dramatic, they're easy to ignore for another six months. A mechanical movement that has run within a few seconds a week for years starts drifting. The crown begins to feel gritty. One morning there's a pale ring of fog under the crystal. None of this looks like an emergency, which is exactly how a fifty-euro gasket turns into a full movement rebuild. Here are the signs worth acting on, roughly in the order they tend to appear.

1. It has started losing or gaining time

You know your watch better than any timing machine does. If a piece that has held four seconds a day for three years suddenly loses a minute a week, that's information, not bad luck. Check it properly before you panic: set it against a reliable reference, wear it normally for a week, and note the deviation at the end. Then check positional variation. Leave it face up overnight, note the error, then crown down the next night.

A healthy movement keeps all positions within a handful of seconds of each other. A worn one can swing twenty or thirty seconds between them, because the oil has migrated away from the pivots and the balance is running dry in some positions and flooded in others. That spread is the clearest early signal that a service is due.

One exception: a watch that suddenly gains several minutes a day after sitting next to a tablet cover, a magnetic clasp or a speaker has probably been magnetised. A watchmaker can fix that in minutes, and it isn't a service.

2. The crown feels stiff, gritty or rough to wind

Winding a hand-wound watch should feel smooth, with resistance that builds evenly as the mainspring tightens. Grit under your fingers means dirt in the stem tube or grease that has dried into wax. On a screw-down crown, grit in the threads quietly shaves metal off the case tube every time you close it, and eventually the crown won't seat properly at all.

Don't force it, don't reach for pliers, and don't add oil yourself. The wrong lubricant turns into a dust magnet. A stiff crown is also a water-resistance issue, since the gaskets live right there, so it belongs at a bench rather than in a drawer.

3. There is condensation under the crystal

Fog inside the glass is the one symptom I'd treat as urgent. It might be a faint haze after a cold walk, or droplets that appear when the watch warms up in the shower. Either way, moisture is inside the case, and it got there because a gasket has hardened, a caseback isn't sealing, or the crown wasn't fully closed. Steel components start to corrode faster than most people expect.

Skip the old tricks. Don't bake it, don't blast it with a hairdryer, don't open the caseback with a kitchen knife. Keep the watch at room temperature, stop wearing it near water, and get it to a watchmaker within days. A dried-out movement and a fresh set of seals is a modest repair; a rusted movement is not.

4. There are new noises, or the power reserve has shrunk

An automatic rotor makes a soft whirr when you move your wrist. It should not scrape, rattle like a tin can, or squeak. A metallic scrape as the rotor swings usually points to a worn bearing or a loose screw, and a high-pitched squeak can be a mainspring running without lubrication. Both get more expensive the longer you wear them.

Then test the reserve. Wind the watch fully, or wear it for a full day, set it down and see how long it runs. If a movement that once managed forty hours now stops overnight, the cause may be a tired mainspring, a slipping automatic winding system, or simply a desk job that doesn't move your wrist enough. Try twenty manual turns before bed for a week before assuming the worst.

5. Pushers, bezels and calendar changes feel wrong

Chronograph pushers should click cleanly, with a firm stop at the end of the travel. Mushy, sticky or slow-returning pushers are common, because those seals are the most exposed on the whole watch, and dried lubricant in the pusher tubes lets in exactly what you'd expect. Never operate pushers in water, and never reset a chronograph while it's still running.

Watch the date too. A date that flips at three in the morning rather than at midnight usually means the hands were set incorrectly at some point, which is a two-minute fix. A date that sits half-turned for hours, or a quickset that stops clicking, is a mechanical problem. On most movements, avoid using the quickset between roughly 9 p.m. and 3 a.m., when the calendar wheels are already engaged.

6. It has simply been a while

Mechanical watches are commonly serviced every four to seven years, though plenty run longer and plenty need attention sooner. Usage matters more than the calendar: a watch worn daily in a dusty workshop ages differently from one rotated gently between a drawer and a desk. Quartz watches need less, but not nothing. Never leave a dead battery inside, because leakage destroys the movement, and have the gaskets checked before the watch goes anywhere near a pool.

Seals harden whether or not you wear the watch, so a pressure test before the first swim of the summer is cheap insurance. If you're booking a service, ask what's included. A proper one usually covers:

• Full disassembly of the movement and ultrasonic cleaning
• Inspection and replacement of worn parts: mainspring, gaskets, sometimes the crown or crystal
• Fresh lubrication, applied by hand, with different oils for different points
• Reassembly and regulation in several positions
• New case seals and a water-resistance pressure test
• Cleaning of the case and bracelet; polishing only on request, since it removes metal

A simple routine to avoid surprises

Write the service date on the receipt and keep it with the box. Once a month, compare the watch against a reference time and note the error in your phone, so you're tracking a trend rather than guessing. Rinse a steel bracelet in fresh water after a day at the beach, and take the watch off before a sauna or a hot shower, since heat and steam shorten gasket life faster than anything else you'll do to it.

When something does feel off, get an opinion early. Most watchmakers will look at a watch and tell you whether you need a service or a five-minute adjustment, and that conversation costs far less than waiting for a small fault to wear a hole in something expensive. A good watch will run for decades. The signs above are simply how it asks for help.

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