What was found
AFTER TAKEOFF, FLAPS UP GOT LEVEL 2 "FLAP DISAG". FLAPS INDICATED 8/7 (LEFT) AND 5/4 RIGHT WING. FLAP HANDLE BACK TO LAST POSITION AND FLAPS WOULD NOT MOVE. HANDLE BACK TO UP NO CHANGE, WHILE MANEUVERING TO LAND FLAPS INDICATED 3/1 AND UP. RETURNED TO MEM. FLAP HINGES, ACTUATORS, CARRIAGES, TRACKS, FLAP VANES, RIG POSITIONS AND IND POSITIONS ALL OKAY. FOUND LT O/B FLAP SPEED SLOWER THAN RT O/B CAUSING A SPLIT. REMOVED RESTRICTOR AND CHECK VALVES ON LT O/B FLAP CONTROL VALVE. FOUND FOD IN CHECK VALVES FILTERS. RESTRICTORS WERE CLEAN. INSPECTED NR 1 AND NR 2 HYDRAULIC ENGINE AND SYSTEM MANIFOLD FILTERS. NO EVIDENCE OF DEBRIS FOUND. REPLACED CHECK VALVES. EXTEND AND RETRACT SPEED NOW MATCH.