Robertson AP 200 Autopilot Issues

[yourtruenorth1]

I have had a Robertson AP 200 Sail autopilot on my CSY 44 that has performed flawlessly for the last 16 years, but as of the last month, has started wandering more and more. The MO is to keep a course when first turned on, but then less and less response from ram, almost as if it loses power.
A quick look at voltage showed good voltage coming into control head, but not much on return.
I took the berth apart to look at connections around quadrant, rudder feedback sensor, and hydraulic pump and all look good. Gave hydraulic pump (Robertson HLD 2000L) a couple raps with wrench and it sprang back to life with a terrible grinding sound and heavy clicking when it initiated a move. Oil reservoir looked to be 2/3 full and no sign of leakage.
Has anybody experienced this or have any ideas? Are these pumps serviceable? I called Simrad/Northstar/Eagle......and all the others, and this pump is still in production. Has anybody serviced or brought one back from the dead?

[Kokopelli-Haehn]

My Robertson AP 200 is powering an all hydraulic steering system but after a short while stops holding coarse on a starboard tack. All linkages and sensors seem to be connected properly. Does anyone have a clue as what the problem might be?