As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE THE AUTOPILOT COULD NOT HOLD AN ALTITUDE. A/C WOULD CLIMB AND/OR DESCENT AT 20-500 FT/MIN. DURING T/S WE FOUND THAT THE AFT CABLE TO THE ELEVATOR SERVO MOUNT WAS SNAPPED IN TWO PIECES. WE HAD TO REPLACE ALL 3 CABLES AND THE SERVO MOUNT AS A PRECAUTION.