What was found
FLIGHT 6046, CMH TO JFK, AFTER LIFT-OFF, THE FLIGHT CREW RECEIVED A L/G AIR/GND FAIL MESSAGE ON EICAS, AND THE GEAR LEVER COULD NOT BE MOVED TO THE UP POSITION. THE QRH WAS FOLLOWED AND THE AIRCRAFT LANDED BACK AT CMH WITHOUT INCIDENT. MAINTENANCE FOUND THE WEIGHT-ON-WHEELS PROXIMITY SWITCH GAPS WERE OUTSIDE LIMITS. THE GAPS WERE ADJUSTED BACK INTO TOLERANCE AND THE PROX SYSTEM OPS CHECKED GOOD.