What was found
PDX FLIGHT NR 2335: NR 1 ENGINE WILL NOT COME OUT OF START AND FEATHER MODE FOLLOWING ENGINE START. NOTICED THAT ON PREVIOUS START, NR 1 ENGINE WAS SLOWER THAN NORMAL TO ACCELERATE FROM FEATHER TO FLIGHT IDLE, APPROX 5-10 SECONDS. AIRCRAFT RETURNED TO BLOCK. MAINTENANCE REMOVED AND REPLACED NR 1 ENGINE OVERSPEED GOVERNOR IAW Q400 AMM TASK 61-20-26-000-801 AND 61-20-26-400-801. OPS CHECK AND LEAK CHECK GOOD. C/W PROPELLER TIME TO UNFEATHER CHECK IAW Q400 AMM TASK 61-20-00-720-801. OPS CHECK GOOD. FEATHERED AND UNFEATHERED NR 1 PROP NUMEROUS TIMES MANUALLY AND WITH ENGINE RUNNING. NO FURTHER DEFECTS NOTED. AIRCRAFT RETURNED TO SERVICE.