As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIR TURNBACK -- RED RIGHT MAIN GEAR LIGHT REMAINED ON WITH GEAR LEVER IN UP POSITION. PUT GEAR LEVER IN OFF POSITION LIGHT REMAINED ON. PUT GEAR LEVER BACK IN UP POSITION AND GOT GREEN LIGHT WITH RED LIGHT. GREEN THEN EXTINGUISHED AND RED LIGHT WENT OUT MINUTES LATER. REMOVED AND REPLACED RIGHT MLG DOWNLOCK SENSOR AND UPLOCK ACTUATOR PER MM.