I found the problem/ solution for this:
„error reports on the autopilot (NAVpilot Furuno 511).
- the motor for the steering is „to hot“;
- a problem with the ruder angle
- „jumping“ rudder angle numbers (without moving the rudder/wheel).“
It is/ was the RUDDER REFERENCE UNIT.
Completely salted. You see it only if you dissasamble it completely.
Take a look at the pictures and you know what to do.
After cleaning, contact spray and corrosionX it works fine again.
May be somebody needs this information/ pictures sometime :-).
AMEL 54 N°119 LADY CHARLYETTE, currently Guadeloupe