What was found
CLIMBING OUT OF PHL, THE NR 1 ENGINE N1 WAS NEAR THE YELLOW ARC AND EPR WAS LOW. AT APPROXIMATELY FL300, A COMPRESSOR STALL AND VIBRATION OCCURRED IN THE NR 1 ENGINE. THE ENGINE WAS SHUT DOWN. THE FLIGHT DIVERTED TO DTW AND LANDED WITHOUT INCIDENT. THE ENGINE WAS REPLACED, RUN-UP, AND CHECKED OK. THE AIRCRAFT RETURNED TO SERVICE.