Thanks everyone who offered advice.
it was a Homer Simpson ‘Doh!’ moment.
After testing everywhere with the multimeter and then a long pause ....
I have always switched on the bow thruster breaker when I switch the windlass breaker, just st n case I might need it. The cockpit controls go live with windlass breaker, but the switches on a he windlass itself are activated through the bow thruster breaker!
you learn something every day. This is original wiring on Santorin 96.
Ian. Ocean Hobo