What was found
BNA - FLT 1661 - AFTER TAKEOFF RDU WHEN LANDING GEAR RETRACTED, LEFT MAIN LANDING GEAR UNSAFE LIGHT REMAINED ILLUMINATED WITH CORRESPONDING DOOR OPEN LIGHT. RECYCLED LANDING GEAR WITH SAME RESULTS. AIRCRAFT DIVERTED TO BNA AND LANDED WITHOUT INCIDENT. REATTACHED LEFT MAIN LANDING GEAR UPLOCK SENSOR ROD ASSEMBLY. SYSTEM GROUND CHECKED NORMAL OPERATION. (M)