As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW OXY PSI SLOWLY DECREASING WITH NO CREW USE. IN ABQ CREW O21300 PSI - 1HR LATER 1200P. FOUND STICKY PRESS TO TEST PLUNGER AT 1ST OBSERVER'S LOCATION. REPLACED O2 MASK & BOX. OPS TEST OKAY. SERVICED CREW O2. NO SYSTEM BLEED DOWN WITHIN 45 MINUTES.