What was found
DURING APPROACH WITH LANDING GEAR DOWN AND FLAPS 20/20, F/O GOT UNRELIABLE AIRSPEED ON PFD FOLLOWED BY SLATS/FLAPS SYS 1 AND 2 FAULT O/H. SLATS/FLAPS CYCLED PER QRH, THE LIGHT/FAULTS CLEARED CONFIGURED AGAIN THE SLATS STUCK AT 15 DEGREES. FOLLOWED QRH FOR SLATS STUCK LANDING. ON FINAL AP FLAP HANDLE AT 40 DEGREES SLATS BROKE FREE AND WENT TO 30 DEGREES SLATS WITH 40 DEG FLAPS. THE LANDING WAS UNEVENTFUL. SLAT/FLAP RETRACT ON THE GND WAS NORMAL. CKD SLAT 0 POSITION AND INDEX OF LT APPU, W/W IPPU AND FPPU, CHK OK. REMOVED AND REPLACED RT APPU ALL AMM 27-81-19-4. REMOVED AND REPLACED RT SLAT TORQUE LIMITER PER AMM 27-84-12-4 OPS CHK NORMAL PER AMM 27-84-00-5 OFF MFG 516A0000-02, SRL K1142, ON MFG 516A0000-03 SRL 00722.