What was found
THE AIRCRAFT WAS ON A MAINTENANCE CHECK FLIGHT DUE TO AN ENGINE CHANGE. AFTER TAKEOFF, THE GEAR WOULD NOT RETRACT. THE AIRCRAFT RETURNED, MAINTENANCE JACKED THE AIRCRAFT, PULLED UP THE FIM AND FOUND THE NOSE GEAR SAFETY PROX SWITCH TARGET LOOSE AND NOT ACTUATING THE PROX SWITCH. THE TARGET WAS SECURED, THE GEAR SWING WAS NORMAL AND THE AIRCRAFT TOOK OFF AND COMPLETED ITS MCF WITH NO FURTHER DIFFICULTIES.