What was found
AFTER MLG SELECTED DOWN, LT MLG INDICATOR LIGHTS DID NOT ILLUMINATE. CREW TESTED BULBS AND PERFORMED A FLY-BY PAST TOWER. CONTROLLER REPORTED THAT MLG APPEARED TO BE DOWN AND LOCKED. A MANUAL MLG EXTENSION PERFORMED AND AIRCRAFT LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE REPLACED THE LIGHT BULBS FOR THE GEAR INDICATION. UPON FURTHER INVESTIGATION IT DISCOVERED THAT SOCKET FOR LT DOWN AND LOCKED INDICATION IN MLG CONTROLLER BROKEN. MLG CONTROLLER REPLACED. OPS CHECK GOOD, AND AIRCRAFT RETURNED TO SERVICE.