As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LGA - UPON GEAR RETRACTION SEVERE VIBRATION FELT IN NOSE OF AIRCRAFT. CONTINUED THROUGH FLIGHT. EMERGENCY DECLARED AND AIRCRAFT LANDED WITHOUT INCIDENT. NOSE GEAR DOOR FOUND OPEN ON ARRIVAL. REPLACED FAULTY LINK ON LEFT HAND NOSE GEAR DOOR. SYSTEM GROUND CHECKED NORMAL OPERATION.