As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 8657, SEA-CLM: RUNAWAY ELEVATOR TRIM ON APPROACH. ELEVATOR TRIM CIRCUIT BREAKER PULLED. LANDED WITHOUT INCIDENT. MAINTENANCE OPS CHECKED AUTOPILOT IN ALL MODES MULTIPLE TIMES AND VERIFIED PROPER OPERATION OF TRIM WHEN MOVING FLAPS. NO DEFECTS NOTED. COULD NOT DUPLICATE PROBLEM. OPS CHECKS GOOD.