S1/8002 Not holding Course

[TravisPWoodard]

Last year, my system worked perfectly. Then I had my steering serviced and my rudder position sensor was left disconnected. This offseason I got everything reconnected and calibrated.

On my last trip, the autopilot engaged, but would not hold exact course. After 15-20 minutes it was off 20 degrees from my standard compass despite the pilot head showing the desired heading.

If it is relevant, my system used to fully disengage manual steering once the auto was engaged. Now, the manual system is not disengaged.

Any ideas on troubleshooting?