What was found
LGA TO CMH - DURING TAKEOFF AFTER A POSITIVE RATE WAS ESTABLISHED THE LANDING GEAR WOULD NOT RETRACT WITH A LANDING AIR/GROUND FAIL ECIAS MESSAGE. CREW FOLLOWED QRH, RETURNED TO FIELD AND LANDED WITHOUT INCIDENT. MAINTENANCE INTERROGATED THE CMC FOR FAULT CODES AND RETRIEVED CODES FOR LG PROX SWITCH AND LG AIR/GROUND LGEU FAIL. THE PROXIMITY SYSTEM WAS TROUBLESHOT AND THE FAULT WAS FOUND WITH THE NOSE LANDING GEAR WEIGHT OFF WHEELS SWITCH. MAINTENANCE REPLACED THE SWITCH AND PERFORMED A COMPLETE SERVICE OF THE NOSE LANDING GEAR STRUT, PERFORMED GEAR SWINGS AND FOUND NO FURTHER FAULTS.