What was found
THE NLG WOULD NOT RETRACT AFTER TAKEOFF FROM IAH. THE NOSE GEAR UNSAFE LIGHT WAS ILLUMINATED AND THE AIRCRAFT WAS STILL IN GROUND MODE. THE AIRCRAFT WAS RETURNED TO IAH. MAINTENANCE FOUND THE NOSE GEAR STRUT FLAT. THE NOSE GEAR STRUT WAS REPACKED IAW MM 32-21-02. IN ADDITION, THE SCHRADER VALVE WAS REPLACED. A NOSE GEAR RETRACTION AND EXTENSION CHECK WAS PERFORMED WITH OPERATION AND INDICATIONS CHECKING GOOD.