What was found
AFTER TAKEOFF FROM KPHL UPON RAISING THE GEAR, THE DOORS "NOT LATCH" LIGHT REMAINED ON. THE CREW CYCLED GEAR PER THE CHECKLIST "DOORS NOT LATCH LIGHT "ON, WITH EXCESSIVE VIBRATION AND NOISE GEAR NOT LATCH "LIGHT" CAME ON. THE CREW RETURNED TO KPHL AND LANDED WITHOUT INCIDENT. MAINTENANCE INSPECTED THE LANDING GEAR AND LUBED THE NOSE LANDING GEAR AND DOORS, LUBED MAIN LANDING GEAR UP-LATCH MECHANISMS. MAINTENANCE INSPECTED THE SWITCHES, JACKED THE AIRCRAFT AND CYCLED GEAR SEVERAL TIMES IAW DACO DC8 MM 32-30-0, THE OPERATIONAL CHECK WAS GOOD.