What was found
"LE SLAT ASYM" MSG DISPLAYED AND LIGHT ILLUMINATED AND CENTER HYD SYS WHITE "ISLN" LIGHT ON P61 PANEL ILLUMINATED. PERFORMED T/S PER FIM 32-09-03 AND INSPECTED L/E PER AMM 27-51-01. REMOVED AND REPLACED ADP AND CENTER ISOLATION VALVE AND CENTER NR 1 PUMP CASE DRAIN FILTER AND ADP PRESS REG SHUTOFF VALVE. OPS AND LEAK CHECK OK PER AMM 29-11-03, 29-11-08, 29-11-19, 29-11-30, 27-58-00. " LE SLAT ASYM" MSG DISPLAYED AND L\E LIGHT ILLUMINATED WHEN FLAPS/SLATS EXTENDED ON TAXI OUT. THEN L\E WOULD NOT RETRACT, T\E FLAPS CAME UP (BLOCK TURN BACK). FOUND NR 3 L\E SLAT POSITION TARGET LOOSE ON INBOARD SENSOR. SECURED TARGET, PERFORMED OPS CHECK PER AMM 27-88-01. REMOVED AND REPLACED PSEU PER AMM 27-1-01. PERFORM