As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FO SIDE OXYGEN MASK BECAME INOPERATIVE AFTER 2 MINUTES OF USE. EMERGENCY PROCEDURE (DESCRIBE UNSCHEDULED LANDING, EMER. DESCENT, ETC) TEXT: FO SWITCHED TO AN ADDITIONAL MASK IN THE COCKPIT. REATTACHED FO’S OXYGEN MASK HOSE IAW B737 AMM 35-12-86. PERFORMED OPS CHECK AND LEAK CHECK IAW B737 AMM 35-12-00 AND LEAK CHECK GOOD NO DEFECTS NOTED.