What was found
A NOTICEABLE VIBRATION WAS COMING FROM NOSE GEAR AREA AFTER TAKEOFF AND GEAR RETRACTION. FLIGHT WAS RETURNED TO BUF AND LANDED WITHOUT INCIDENT. MAINTENANCE FOUND LEFT NOSE GEAR DOOR STOP CABLE BROKEN, LATCH MECHANISM STIFF, AND LEFT FORWARD DOOR LINK NOT LOCKING IN RETRACTED POSITION. REPLACED CABLE, LUBED LATCH MECHANISM, AND REPLACED LINK ASSEMBLY. ALSO, REPLACED DOOR DUE TO DAMAGE INCURRED, OPERATIONAL CHECK NORMAL.