My
Simrad had the same symptoms when the drive
brushes crapped out, but it was on their HLD 2000L drive, not the Octopus. I'd try to find a spare set of
brushes.
Try:
1. Run the
rudder back and forth with manual AP at
anchor, and see if the
rudder position follows smoothly . Check
current consumption--should be 2-3 amps, and voltage at the AP terminal should be over 12v. If the position is twitchy around the zero rudder position, the RFU needs replacing, but you can use it for a while if you rotate the RF300 base 10-15 degrees and recalibrate.
2. Under sail, drive the
boat yourself--does the
helm feel heavy?? Then put AP on and check
current consumption--should be no more than 5-7 amps in the peaks. Your rudder system may be starting to seize up.