I found a tip regarding retraction problem which could avoid desperation:
After replacing wire harness, push-pull cables and get an overhauled motor and gear transmission:
During retraction, the motor was chattering for the plunger of brake coil still touched from time to time the (brand new) rubber disc. So CB popped of course.
I inverted the wires connection to the brake coil and the retraction worked fine. The brake coil firmly retracted the plunger.
Trying to get an explanation, I put a steel needle on the plunger and it stays stuck which means that the plunger (soft iron that normally can not be magnetized) has been slightly magnetized (aircraft is 50 years) which probably explains a better retraction after inversion of lead wires to the coil.
I hope it helps.
Have nice flights