What was found
AFTER TAKEOFF WHEN GEAR WAS RETRACTED, RED UNSAFE LIGHT STAYED ON, LEFT MAIN GEAR DOOR LIGHT WAS ON. CYCLED GEAR, OPS CHECKED NORMAL. REMOVED AND REPLACED LEFT MAIN LANDING GEAR DOOR UPLATCH AND INDICATION IAW DC8 MM 32-60-00 AND ALSO CHECKED MIN ROLLER CLEARANCE OF .032", ALL CHECKED GOOD. LEFT MAIN LANDING GEAR DOOR INDICATION CHECKED GOOD IAW SAME.