As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AUTOPILOT WOULD NOT DISENGAGE IN PITCH CONTROL DUE TO SHORTED Q-211 (PITCH ENGAGE TRANSISTOR) SUPPLYING CONTINUOUS POWER TO PITCH SERVO-CLUTCH. AUTOPILOT WAS ABLE TO BE DISENGAGED BY HOLDING DOWN AUTOPILOT DISCONNECT BUTTON AND PULLING AUTOPILOT CIRCUIT BREAKER.