What was found
FLAPS SYS 1 AND SYS 2 LIGHT CAME ON WHEN SELECTING FLAPS 20 ON APPROACH. FLAPS STUCK HALFWAY BETWEEN 15 AND 20. EXECUTED MISSED APPROACH, CYCLED FLAPS SUCCESSFULLY AND EXECUTED NORMAL SLAT/FLAPS 30/40 APPROACH. REMOVED AND REPLACED NR1 AND NR2 SFCC IN REF TO AMM 27-51-18-4. CHECK FLAP DRIVE SHAFTS FOR FREEDOM OF MOVEMENT WITH NO DISCREPENCIES NOTED. PERFORMED OPS CHECK OF FLAPS RUNNING THEM FROM 0-20 THRU 15 AND ON TO 40 SEVERAL TIMES WITH ENGINES RUNNING AND NO FAULTS NOTED. OPS CHECK IN REF TO AMM 27-54-00-5. PERFORMED BITE CHECK OF NR1 AND NR2 SFCC IN REF TO AMM, ALL TEST PASSED. ACFT OK FOR SERVICE.