What was found
ENGINE NR 1 START VALVE STUCK INTERMITTENTLY DURING ENGINE START. GOOD APU PRESSURE ENGINE START SWITCH, GRD. NO START VALVE OPEN LIGHT AND NO N2 ROTATION, MADE 3 ATTEMPTS TO START (UNSUCCESSFUL). UNDER CONSULTATION WITH ALASKA MX CONTROL, START VALVE OPEN LIGHT CAME ON 4TH ATTEMPT AFTER 18 SECONDS WITH NR 1 ENGINE START SWITCH IN GRD, GOOD START. GROUNDED-YES. ACCOMPLISHED B737-800 FIM 80-07 TASK 804 VOLTAGE GOOD. REMOVED & REPLACED NR 1 ENG START VALVE, PER SAME. OPERATIONS & LEAK CHECK GOOD.