What was found
DURING CRUISE ALTITUDE 35000, LT MAIN CARGO DOOR UNLOCK INDICATION CAME ON NO DISCERNABLE CHANGE IN CABIN PRESSURE, LIGHT REMAINED ON UNTIL 200 FL. DURING TROUBLESHOOTING WITH MAIN CARGO DOOR CLOSED & LOCKED FOUND DOOR WARNING SWITCH 49WS ADJUSTMENT AT MINIMAL CONTACT AT LOCKED POSITION. USED SHIMS, MULTIMETER & ACFT INDICATIONS, ADJUSTED 49WS SWITCH IAW AMM. OPS CHECKED NUMEROUS TIMES WITH NO FAULTS.