What was found
DURING GEAR EXTENSION, LEFT MAIN INDICATED RED ONLY. CREW PERFORMED A MISSED APPROACH, CIRCLED AND PERFORMED A MANUAL GEAR EXTENSION. FOLLOWED QRH PROCEDURE. AS A RESULT, LEFT MAIN AS WELL AS RIGHT MAIN AND NOSE ALL INDICATED DOWN AND 3 GREEN. FLIGHT THEN PERFORMED A TOWER FLYBY TO CONFIRM EXTENSION. FLIGHT LANDED WITHOUT INCIDENT. AN EMERGENCY WAS DECLARED. MAINTENANCE ACCOMPLISHED AMM TASK 32-32-00-715-001 MAIN LANDING GEAR OPERATIONAL TEST. UNABLE TO DUPLICATE. OPS CHECKS OK. LUBRICATED UPLOCK ASSEMBLY'S AS PRECAUTION.