Paul’s description above is good but there mat be another bit of complexity.
Based on the wiring of our 45e, which of course may not be the same, there is another engine interlock relay (incorrectly wired by Dufour on our boat, but that is another story) which Paul has not described.
The system on the 45e consists of;
1) The contactor, located just outside the anchor locker. This is internally just a pair of high current relays which depending on whether the up or down control buttons are pressed, connects 12v to either the up or down terminals on the windlass motor.
2) A high current fuse or in our case circuit breaker in the high current connection from the “centre” terminal of the contactor to the battery +.
3) A “windlass on” switch on the control panel.
4) A fuse (low current) on the back of the control panel.
5) An engine interlock relay (mounted behind the control panel). This prevents the windlass from being operated unless the engine is running and the alternator charging! It is to protect the batteries but in my opinion is a safety issue since in the case of engine failure it prevents the windlass from operating. I have fitted an emergency override.
When the alternator is charging this relay is energised and connects 12v from the battery through the control panel switch and control panel fuse to the CONTROL side of the contactor / up down switches.
The main power feed to the contactor is separately supplied via the fuse / circuit breaker.
Paul’s trouble shooting is sound.
1) does the contactor click when you press either the up or down buttons? If so then the whole of the low current side is working and the problem lies in the contactor contacts or high current supply. If either up or down buttons produce a click but no windlass drive then the high current circuit is faulty (fuse/circuit breaker/ terminal corrosion, or there is a motor / motor wiring fault.
2) If no click then 12v is not reaching the control side of the contactor or the contactor is faulty. Discriminate by checking whether 12v reaches the contactor control terminals (the small ones). If present then the contactor is faulty, if absent then just follow the control circuit back to find the fault. Is there power to the control panel. Is the control panel windlass fuse intact, OK, then is there power to the windlass switch, OK, then is there power to the engine interlock relay if fitted. If the relay is fitted, does it pull in when the engine is running, and so on!
Half an hour(ish) with a test meter!
Hope this helps.
PS it is not difficult to dismantle the windlass / motor. The only serviceable parts are really the brushes (unlikely to have worn away) these are Bosch parts on Quick winlasses (don’t pay Quick prices!).