What was found
LANDING GEAR UNSAFE LIGHT ILLUMINATED DURING CRUISE FLIGHT WITH LEFT MAIN LANDING GEAR DOOR 'NOT LATCHED' LIGHT ILLUMINATED. RECYCLED GEAR, NO CHANGE. ADJUSTED LEFT MAIN LANDING GEAR PROXIMITY SWITCH TARGET STOP. REPLACED LEFT GEAR DOOR SPRING IAW DC8 MM 32-31-5. PERFORMED TEST IAW DC8 MM 32-6, OPS CHECKED GOOD.