As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING OPERATION OF AIRCRAFT CREW REPORTED OSCILLATIONS IN VERTICAL MODE OF FLIGHT DIRECTOR WITH AUTOPILOT DISCONNECTING. THE AUTOPILOT SERVO WAS FOUND FAULTY AND WAS REPLACED. A SATISFACTORY OPERATIONAL CHECK WAS PERFORMED AND AIRCRAFT WAS RELEASED FOR CONTINUED SERVICE.