What was found
AFTER TAKEOFF, RETRACTED GEAR, RT MLG RED LIGHT REMAINED ILLUMINATED. RECYCLED GEAR TO DOWN, ALL NORMAL WITH 3 GREEN, RETRACTED GEAR STILL WITH RT MLG RED LIGHT. GEAR DID RETRACT WITH GEAR HANDLE IN "OFF", RT MLG EXTENDED IN UP, ALL GEAR RETRACTED. REMOVED AND REPLACED RT MLG UP ACTUATOR PER MM.