Now I have a flakey AP. The motor stopped working after hours of pounding to weather in 30+ knots of wind. The solenoid would engage, but no motor. When I got to port I checked the following:
1) Opened up Raymarine course computer, and checked 30A fuse for drive motor. Check OK.
2) Check output voltage to motor from course computer, with AP engaged, tried changing course to starboard then port, and voltage was reversed as it should. However voltage without load was +-6v which seems odd -- I think it should be 12v.
3) Check wire continuity between course computer and motor. Check OK. Reconnect all wires. It works! (If I worked in a marina I could charge $500 for that).
4) FYI drive motor is a sealed unit. Can't access internal motor wires. It's a Whitlock Duo80

Next morning, leaving harbor the AP works for about 10 minutes, then stops again. Sailed a few hours hand steering, then started the AP just to engage the clutch to hold the wheel, lo and behold -- it works again! It's been working since then. However, I don't trust it.

Anyone have ideas about where the gremlin is?