As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW OXYGEN BOTTLE DROPPED FROM 900 PSI TO 700 PSI IN APPROXIMATELY ONE MINUTE DURING CRUISE. FLIGHT DIVERTED TO MKE AND LANDED WITHOUT INCIDENT. MAINTENANCE REPLACED CREW OXYGEN BOTTLE REGULATOR AND FIRST OFFICER'S OXYGEN REGULATOR. LEAK AND OPERATIONAL CHECK NORMAL.