I recently bought a used MK 65 Auto pilot trolling motor. When I set the AP it will track ok for a short time then trun alnost 180 deg. pretty quickly, like it's trying to keep me in one spot.
I've tried just punching the set button and holding it down for a couple of seconds. But it wants to do this either way. What am I doing wrong, or is there something wrong with the motor?

Jim, it sounds like the board that controls the compass is bad. I have the same trolling motor in the Rip Tide. I took it to southwestern parts to have fixed. It works good if the wind doesn�t get to strong and throws if off course to fast. Good Luck