Claude:

Those autopilots need to be coupled to your avionics (specifically attitude indicator and heading indicator) quite closely. If these have been replaced over the years you are likely out of luck. Are they still connected to the attitude indicators?

Those old autopilots use high frequency resonant tank circuits with capacitors and coils in the instruments in parallel. Variations in the instruments change the value of the capacitance or inductance, this changes the frequency, and the servo is actuated until the feedback capacitor returns the frequency to the center. They are touchy and subject to temperature variation and so forth.

Those knobs are likely attached to some sort of variable air gap capacitor. You would need to open the case and carefully clean and lubricate the capacitor shaft bearings without leaving any residue behind on anything.

There are service manuals for those available on line but I am afraid I don’t have any for that model.

I’ve managed to restore to function an even older “Mitchel Airboy” based Piper Autocontrol II. It wasn’t easy but other than a rebuild of an ancient AN attitude indicator (cost of one AMU) it was relatively inexpensive. Just a lot of careful cleaning and research and helpful guidance for the shop.

William

Claude:

There is indeed: a lever that moves the gear motor pinion down into the slip disc arrangement and that also closes a switch that engages the electronics.

I found a shop in the states that would rebuild the old AN style gyros (direction indicator and artificial horizon): http://www.flyaqi.com/gyro.htm

They did a very good job on my artificial horizon.

Good luck!

William