What was found
MIA - FLT 1578 - EN ROUTE MIA-ATL, ON TAKEOFF, NOSE LANDING GEAR DID NOT RETRACT PROPERLY. SEVERAL LOUD THUMPS HEAD AT HIGH SPEED ON TAKEOFF ROLL. RETURNED MIA WITHOUT INCIDENT. INSTALLED SERVICEABLE NOSE GEAR STRUT. ACCOMPLISHED NOSE GEAR SWING. SYSTEM GROUND CHECKED NORMAL OPERATION. (M)