What was found
LE SLAT ASYM EICAS ALERT ON FINAL @ 1300 MSL WHEN FLAPS SELECTED TO 25 DEGREES . EXECUTED MISSED APPROACH @ 700 . LEVELED AT 2000 CLEANED AIRCRAFT TO FLAPS 5 AND NOTICED LE SLAT ASYM EICAS EXTINGUISHED WHEN FLAPS RETRACT TO 20. REATTEMPED FLAP EXTENSION TO 25, EICAS LE SLAT ASYM ILLUMINATED WHEN FLAPS PASSING 20 TO 25. RETRACTED FLAPS TO 5 AND RAN FOLLOWED QRH PROCEDURES. R/R PSEU REF AMM 31-70-04-4-99. PERFORMED LEADING EDGE SLAT TEST (507) ON PSEU TEST PASSED. EXTEND AND RETRACT FLAPS/SLATS WITH HYDRAULICS MULTIPLE TIMES FROM 0 TO 30 WITH NO FAULTS OR DEFECTS NOTED. EXTEND AND RETRACT FLAPS/SLATS WITH ALT OVERIDE SOURCE NO FAULTS OR DEFECTS NOTED REF AMM 27-58-00-5.