As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE IN CRUISE FLIGHT AT FL260, AUTOPILOT HOLDING ND MISTRIM ANNUNCIATOR ILLUMINATED. ELEVATOR TRIM WAS FROZEN. TRIM OPERATED NORMAL AT DURING DESCENT TO LOWER ALTITUDES 13,000FT. FLIGHT DIVERTED. MAINTENANCE PERFORMED THE REQUIREMENTS OF PITCH TRIM NTO LETTER. A SUCCESSFUL OPERATIONAL CHECK FLIGHT WAS PERFORMED. AIRCRAFT WAS RETURNED TO SERVICE.