As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FIRST OFFICER'S OXYGEN MASK RESET SWITCH BROKEN. SWAPPED FIRST OBSERVERS MASK UNIT TO FIRST OFFICERS POSITION CARRIED OUT OPS AND LEAK CHECKED OK. REPLACED O2 MASK ASSEMBLY. PERFORMED LEAK CHECK AT CONNECTIONS. O2 AND MICROPHONE OPS CHECKED NORMAL.