What was found
DURING CRUISE, CAPTAIN NOTICED 3 RED UNSAFE LIGHTS ILLUMINATED ON THE ANNUNCIATOR PANEL, AS WELL AS THE UNSAFE LIGHT IN THE MLG HANDLE. F/O AND CAPTAIN NOTICED MLG DID NOT EXTEND, AS THERE WERE NO SOUNDS. A GO AROUND WAS INITIATED. COMPLETED ALTERNATE MLG EXTENSION. MLG FREE FELL INTO EXTENDED POSITION (3 GREEN). NO EMERGENCY DECLARED, LANDING WAS UNEVENTFUL. MX TROUBLESHOT, FOUND MLG SELECTOR VALVE AT FAULT. SELECTOR VALVE REPLACED. ACFT RELEASED FOR SERVICE.