Help with my Raymarine wheel drive

[svlamorocha]

Hello everyone
I know that wheel-drive autopilots always give trouble but I have no money to upgrade..
After several months of working very well, now the wheel drive "disengages" (ie the lever opens as if an invisible helmsperson had moved it) by itself every once in a while....
(It may or may not be relevant that the rudder angle feedback unit stopped working while the boat was chartered out; I think that this should not disable the system because it has an S1G unit with gyro, hence should be able to work without rudder angle feedback...)
Any ideas as to how to fix this?
Thanks

Charlie