As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FO CREW O2 MASK IN TEST POSITION 02 FLOWS LONGER THAN NORMAL. SWAPPED MASKS WITH O2 MASK FROM SECOND OBSERVER'S SEAT. ACCORDINGLY SECOND OBSERVER'S SEAT RENDERED INOPERATIVE, NOT TO BE OCCUPIED. REPLACED O2 MASK, SLIDING OBSERVER`S SEAT RETURNED TO SERVICE.