What was found
UPON DEPARTURE, WHEN LANDING GEAR WAS RAISED, A LOUD NOISE WAS HEARD AND A LARGE AMOUNT OF VIBRATION WAS FELT. LANDING GEAR WAS EXTENDED AND THREE GREEN INDICATED. AIRCRAFT LANDED UNEVENTFULLY. FOUND LEFT FORWARD NOSE LANDING GEAR DOOR OPEN. MANUALLY CLOSED DOOR AND DISCOVERED DOOR NOT LATCHING PROPERLY. INSPECTED DOOR CLEARANCE AND FORWARD STOP CLEARANCE. FOUND TO BE WITHIN LIMITS. DISCOVERED EXCESSIVE DIRT AND LUBRICANT ON DOOR LATCHING MECHANISM. CLEANED AND LUBED DOOR MECHANISM. MANUALLY OPENED AND CLOSED DOOR AND GOT POSITIVE LOCK EACH TIME IAW B767 AMM 32-22-02.