What was found
DURING APPROACH, THE LANDING GEAR DOOR OPEN LIGHT REMAINED ON AFTER GEAR WAS EXTENDED. GO-AROUND PROCEDURES WERE EXECUTED AND GEAR WAS RECYCLED. DOOR OPEN LIGHT STAYED ON, EMERGENCY GEAR EXTENSION PROCEDURES WERE UTILIZED AND A SUCCESSFUL LANDING WAS ACCOMPLISHED ON SECOND ATTEMPT. MAINTENANCE FOUND LEFT MAIN GEAR SLOW TO RETRACT. REPLACED RESTRICTOR VALVE, OPERATIONAL CHECK NORMAL. DOOR SKID PADS WERE REPLACED DUE TO DAMAGE INCURRED ON LANDING.