What was found
ORD - FLT 350 - AFTER TAKEOFF ORD-LGA, NOSE GEAR UNSAFE LIGHT ON RETRACTION. GEAR LOWERED AND SAFE LIGHTS ILLUMINATED. AIRCRAFT RETURNED TO ORD AND LANDED WITHOUT INCIDENT. ADJUSTED NOSE GEAR UP PROXIMITY SENSOR, CYCLED LANDING GEAR SEVERAL TIMES. SYSTEM GROUND CHECKED NORMAL OPERATION. (M)