What was found
DURING CRUISE, A/C BEGINNING TO PITCH UP & DOWN SLIGHTLY WITH AUTOPILOT ENGAGED. DISENGAGED AUTOPILOT IN ORDER TO RE-TRIM A/C. DURING PROCEDURE RUDDER TRIM FOUND IMMOBILE. ATTEMPTED SMALL RUDDER DEFLECTION WITH RUDDER PEDALS & FOUND THEM TO BE IMMOBILE. DECLARED AN EMERGENCY AND DIVERTED TO CYWG. DURING DESCENT AT APPROX 9000 FT, RUDDER BEGAN TO FREE ITSELF & FUNCTION CORRECTLY. A/C CONTINUED ITS APPROACH & LANDED AT CYWG W/O FURTHER INCIDENT. MX INVEST WITH ASSISTANCE OF BOEING SERVICE LETTER 727-SL-27-24 INDICATED RUDDER TRIM ACTUATOR TO BE LACKING SUFFICIENT LUBE RESULTING IN HIGHER THAN NORMAL INPUT FORCE. RUDDER TRIM ACTUATOR & RELATED PARTS LUBED IAW SERVICE LETTER & MM. A/C RETURNED TO SERVICE.