As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 1639, IAH TO PHL - THE CAPTAIN RETURNED TO IAH DUE TO LANDING GEAR HANDLE WOULD NOT RAISE AND THE LANDING GEAR WOULD NOT RETRACT. MAINTENANCE TROUBLESHOT PROBLEM TO THE NOSE LANDING GEAR WEIGHT ON WHEELS SENSOR NUMBER ONE. REMOVED AND REPLACED SENSOR AND PERFORMED GEAR SWING OPERATIONAL CHECK.