What was found
PILOT REPORTED THAT ON APPROACH INTO KMIA, THE RT MLG LIGHT REMAINED RED WHEN GEAR WAS SELECTED DOWN. THE PILOT USED THE MANUAL EXTENSION TO GET THE RT MLG INDICATING DOWN & LOCKED, LANDED WITHOUT INCIDENT. AIRCRAFT WAS FERRIED TO KOPF WHERE MX PERFORMED SEVERAL GEAR SWINGS BUT COULD NOT DUPLICATE THE PROBLEM. GEAR WAS SERVICED IAW THE ITEMS LISTED IN THE AMM 32-00-00 & RIGGING CHECKED AS A PRECAUTION.