Windlass started slipping last winter trip.
Motor had been rebuilt 2 years ago.
Feared the worst that a gear had stripped or one of the keys in the shaft lost its grip.
After several times disassembling and reassembling trying to figure out just what was wrong, I noticed the claw coupling (clutch) which engages the round part of the worm gear (large gear in picture) was sticking and not engaging all the time.
A good cleaning, new gear oil and back in business as if new.
Parts for this Vetus winch might not have been easily available so I am glad I dodged the $300 dollar part bullet and really happy to dodge the $2000 new windlass bullet had the parts not been available.
Some winches are very similar inside, and very easy to disassemble. Don't be afraid to try!