What was found
EWR---CO2049, CREW REPORTED, "ON LIFT OFF, RECEIVED AIR/ GROUND FAIL MESSAGE ON EICAS. GEAR WOULD NOT RETRACT. MESSAGE DID NOT GO AWAY. RETURNED TO NEWARK." MAINTENANCE TROUBLESHOT AND FOUND NOSE LANDING GEAR STRUT STICKING. SERVICED STRUT IAW EMB145 MM 32-20-01, OPS. CHECKED GOOD ON GROUND, REQUESTED TEST FLIGHT TO VERIFY REPAIR. AIRCRAFT TEST FLOWN SATISFACTORY. AIRCRAFT RETURNED TO SERVICE.