What was found
WHEN LANDING GEAR HANDLE WAS POSITIONED DOWN ALL RED SYSTEM LIGHT LIT UP AND THEN LEFT MAIN GEAR A GREEN LIGHT LIT UP, BUT NONE OF THE GEAR EXTENDED ELECTRICAL OVERIDE PROCEDURE WAS USED, GEAR EXTENDED. REPLACED LANDING GEAR CONTROL BOX WITH SERVICEABLE UNIT IAW MM 323000, OPS CHECKS GOOD. P/N ON: 12038594001, S/N: 12004JR, S/N OFF: 120151.