As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB, THE FIRST OFFICER APPLIED CONTROL INPUTS TO THE RUDDER TRIM. AFTER REMOVING HAND FROM THE TRIM CONTROL KNOB, RUDDER TRIM CONTINUED UNCOMMANDED MOVEMENT TO THE RIGHT. TRIM MOVEMENT STOPPED AFTER COMMANDING LEFT RUDDER TRIM. NO FURTHER PROBLEM NOTED BY FLIGHT CREW. MAINTENANCE REPLACED THE RUDDER TRIM CONTROL MODULE. OPERATIONAL CHECK OK.