What was found
DURING CLIMB, RUDDER TRIM WAS USED TO COORDINATE FLIGHT AND NOTICED SWITCH HAD SUDDENLY NO SPRING TENSION TO THE LT AND RT. THOUGHT IT WAS A LOOSE SET SCREW PROBLEM. NOTICED WHEN APPLYING RUDDER TRIM AND RELEASING SWITCH THERE WAS STILL TRIM BEING APPLIED, PRESSED THE MSW SWITCH AND MOTION STOPPED EVEN AFTER RELEASING THE MSW SWITCH. MOVED SWITCH TO OPPOSITE DIRECTION AND IT WOULD FOLLOW COMMAND BUT WOULD NOT STOP WHEN RELEASED. ABLE TO STOP THE TRIM MOTION BY MANUALLY CENTERING SWITCH AS NOT TO RECEIVE ANY TRIM MOTION. APPLIED RUDDER FORCE WITH PEDALS TO VERIFY CONTROLLABILITY AND RETURNED TO THE AIRPORT. FOUND THAT RUDDER TRIM SWITCH HAD FAILED INTERNALLY. REPLACEMENT PARTS ORDERED FROM MFG AND INSTALLED AND WERE NOTIFIED OF THE INCIDENT.