What was found
AFTER TAKEOFF GEAR WOULD NOT RETRACT. EICAS MESSAGE LANDING GEAR AIR/GRND FAIL. RAN QRH CHECKLIST, CONTACT DISPATCH AND MTX AND RETURNED TO MCO FOR LANDING. NO EMERGENCY WAS DECLARED, BUT EMERGENCY EQUIPMENT WAS DISPATCHED. FOUND LF AFT (WOW) PROXIMITY SENSOR FACE CRACKED. REMOVED AND REPLACED PROXIMITY SENSOR, PERFORMED GEAR SWING OPS CHECK GOOD.