As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
F/O'S OXYGEN HARNESS FAILS TO INFLATE (IS LEAKING). CREW COMMENTS: HARNESS CLIP IS BROKEN HARNESS NOT ATTACHED AT TOP LEFT TEMPLE. SWAP F/O MASK WITH 2ND OBSERVER MASK. COMPLY WITH MEL FOR 2ND OBS SEAT. SWAPPED F/O WITH 2ND OBSERVER MASK. 2ND OBS SEAT BLOCKED PER MEL. RPLC'D MASK ON 2ND OBSERVER WOULD NOT TEST AND REST, NEEDS O2 BOX. REPLACED MASK ASSEMBLY PER MM.