As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING ENGINE RUN NOTICED DUCT SPLIT UP TO APPROXIMATELY 40% BEFORE PRESSURES EVENED UP. GROUNDED - YES. REMOVED AND REPLACED #1 ENG HIGH STAGE VALVE REF B737-900 AMM 36-11-06 REQUIRES BLEED AIR CROSSOVER TEST AND HIGH STAGE VALVE OPS CHECK. LEAK CHECK OF HIGH STAGE VALVE GOOD. PERFORMED CROSSOVER TEST PER AMM 36-11-00-710-801.