It is still surprising to me just how often this is the whole problem. It is the first check on the preliminary checks as you can test it as the customer is handing you the watch.

If the winder is out and the watch starts when you put it in the run position I never assume it is the problem straight away. Find out if the watch has been

If it is one of the first 2, then the winder out is not your problem, only if they say the 3rd, stopped once, is it likely to be the winder out.

Even if you suspect it is just the winder in the time set position, do not set it running and assume it is just that. There is a chance that it is still the battery and if it is, you will earn money on the battery replacement. Carry on with the battery replacement process until you find the battery is full.