As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CAPTAIN'S PRESS TO TEST AND RESET LEVER ON O2 BOX FAILS TO GIVE PROPER TEST NR O2 FLOW OR INTERMITTENT FLOW TO IRIS. SWAPPED CAPTAIN'S AND NR 2 COURIER O2 MASK BOX ASSY'S IAW MM 35-11-51-4-99. CAPTAINS O2 MASK TESTED GOOD. REMOVED AND REPLACED MASK AND BOX PER MM 35-11-51. SYSTEM OPS GOOD.