As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW O2 LOW. REPLACED F/O'S, 1ST-OBS, AND 2-OBS CREW O2 MASKS. LEAK CK'D ALL 3 MASKS AT THEIR LOCATIONS FOUND NO LEAKS. FOUND CREW O2 CK VALVE FITTING CRACK AT THE THREADS. REPLACED CREW CK VALVE, SERVICED CREW O2 TO 1740 & PASS O2 TO 1800 NO LKS DETECTED.