As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CAPTAIN`S SIDE O2 MASK LEAKING IN HOSE ASSY SWAPPED CAP AND OBSERVER MASK IAW AMM 35-11-12 DEF OBSERVERS O2 MASK IAW MEL 35-10-01 PLACARD INSTALLED ENTERED INTO MM02, OBSERVERS MASK DISCONNECTED. INSTALLED ORIGINAL MASK BACK INTO THE OBSERVER SEAT AND INSTALLED NEW O2 MASK INTO CAPTAIN`S SIDE O2 IAW AMM 35-11-12. OPS AND LEAK CHECKS PASSED. OK FOR SERVICE. MM02 UPDATED PLACARD REMOVED.