As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ORD T/636 EN ROUTE ORD-BOS UNABLE TO RAISE NOSE GEAR ON TAKEOFF. RETURNED ORD AND LANDED WITHOUT INCIDENT. FOUND NOSE STRUT FLAT AND PERFORMED FULL SERVICE PER MM 32-21-02. REPLACED SCHRADER VALVE AND RING ASSEMBLY. SYSTEM GROUND CHECKED NORMAL OPERATION.