What was found
MAIN CABIN DOOR WILL NOT UNLOCK. MED KEY LOCK CYLINDER IS NOT ROTATING, KEY INSERTS BUT NO MOVEMENT.CLEANED AND LUBRICATED MULTIPLE TIMES. LUBED BACKSIDE OF LOCK ASSEMBLY. KEY TURNED BUT VERY DIFFICULT. FOUND LOCKING TAB OUT OF POSITION CAUSING IT TO JAM. RE POSITIONED LOCKING TAB. PERFORMED AMM 52-11-00-200-801-A - MAIN-DOOR LOCKING AND ACTUATING MECHANISM - GENERAL VISUAL INSPECTION. NO DEFECTS NOTED. PERFORMED LUBRICATION OF MED LOCKING MECHANISM IAW AMM 52-11-21 OPS CHECKS GOOD. NO DEFECTS NOTED. REF AMM 52-10-00.