As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT COMPRESSOR STALL AT FL390 IN LT-MOD CHOP,N1 WENT DOWN TO 74 PERCENT WHILE EGT DID NOT RISE. THE ENGINE BORESCOPE REVEALED 9TH STAGE HPC (HIGH PRESSURE COMPRESSOR) DAMAGE WAS OUT OF ALLOWABLE LIMITS, AND ENGINE WAS REPLACED. AFTER ENGINE TEARDOWN THE DAMAGE WAS CONFINED TO THE 9TH STAGE HPC. THE PNEUMATIC SYSTEM PRE-COOLER WAS REPLACED DURING THE ENGINE CHANGE, AND IS SUSPECT AS BEING THE CAUSE OF DAMAGE TO HPC.