What was found
AFTER ROTATION AIR CREW HEARD A CLUNKING NOISE AND LANDING GEAR WOULD NOT RETRACT. GEAR HANDLE WILL NOT MOVE INTO RETRACT POSITION. ALL GEAR DOWN AND LOCKED "GREEN" LIGHTS STAYED ILLUMINATED. CREW PERFORMED A FLY BY AND HAD TOWER VERIFY THAT GEAR WAS DOWN. CREW RETURNED TO BASE TO. AFTER LANDING, WE INSPECTED THE AIRCRAFT AND LANDING GEAR AND DISCOVERED THAT THE NOSE GEAR CENTERING ARM WAS DEFORMED AND NOT MAKING PROPER CONTACT WITH THE CENTERING SWITCH PREVENTING THE RETRACT. WE REPLACED THE CENTERING ARM AND PERFORMED SEVERAL SATISFACTORY OPS CHECKS. AIRCRAFT WAS RETURNED TO SERVICE WITH NO FURTHER LANDING GEAR ISSUES.