As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CREW REPORTED STAB TRIM MOVEMENT WITHOUT PILOT INPUT IN FLIGHT. THE AIRCRAFT WAS FERRIED TO DAY WHERE MAINTENANCE FOUND A FAILED AUTOPILOT ELEVATOR SERVO. THE SERVO WAS REMOVED & REPLACED IAW CRJ200 AMM 22-11-24-000(400)-801. OPERATIONAL TESTS OF AUTOPILOT & STAB TRIM SYSTEMS WERE GOOD. THE AIRCRAFT WAS RELEASED FOR SERVICE.