Garmin AutoPilot CCU Mounting Bracket Failure

There is a thumbscrew on the CCU (AKA compass ball) that holds the bracket tight against the ball. In my case the plastic screw hole split allowing the ball to move. My unit is 9 years old so perhaps the aging plastic had something to do with the failure. A replacement bracket can be found online for about $10.00. Garmin Part No. is 010-11173-00.
Do not overtighten the screw, just snug it up.

oh I will check the mount.

my autopilot does a great job with heading hold and steering by changing the compass setting; it just does the over steer when on an autorouting guidance. I can be 50 feet left of the intended course running basically in parallel without autopilot / follow a route on. I put the autopilot on and the boat steers hard to starboard over the intended routing course and then slowly comes back onto the intended route by steering to port slightly. this slow return takes half a mile. the initial starboard turn takes 50 feet!

I need to check what happens if I am slightly to the right of the intended route and see if the symptoms are as bad: I wonder whether the offset rudder has anything to do with this behaviour.