What was found
PDX - ON FLIGHT 2431, RETURNED TO GATE, DURING TAKEOFF UPON GEAR RETRACTION, THE RIGHT GEAR DOOR AMBER LIGHT REMAINED ILLUMINATED. THE AMBER LIGHT EXTINGUISHED ON ITS OWN. NORMAL GEAR EXTENSION AND LANDING IN PDX. MAINTENANCE REMOVED AND REPLACED UPLOCK ASSY, UPLOCK PROX SENSORS, MLG DOOR ACTUATOR, MLG AFT DOOR MECHANICAL SEQUENCE VALVE, SOLENOID VALVE, INLINE RESTRICTORS. OPERATIONAL TEST GOOD. AIRCRAFT RETURNED TO SERVICE.