What was found
FLT 4306 - DURING TAKEOFF FROM ATL-CLT, THE CREW SELECTED THE GEAR HANDLE UP, BUT THE NOSE GEAR DID NTO RETRACT. QRH PROCEDURES WERE COMPLIED WITH, AN EMERGENCY DECLARED AND THE AIRCRAFT RETURNED TO ATL, LANDING SAFELY. MAINTENANCE ADJUSTED THE NOSE DOOR PROXIMITY SENSOR SWITCH ON THE RIGHT SIDE AND ALSO CLEANED THE NR 2 DOWN LOCK SWITCH CANNON PLUG ON THE NOSE DOOR IN ADDITION TO CYCLING THE GEAR TWENTY TIMES WITHOUT ANY DEFECTS NOTED. OPERATIONAL CHECKS GOOD. AIRCRAFT OK FOR SERVICE. (M)