What was found
CAPTAINS SIDE OXYGEN MASK NOT TESTING PROPERLY. WHILE HOLDING PRESS TO TEST, O2 FLOW CONTINUES WHEN IT SHOULD NOT, & MARKER REMAINS YELLOW, NOT BLACK. SWAPPED CAPTAINS SIDE 02 MASK WITH OBSERVERS SIDE 02 MASK, PROBLEM FOLLOWED DEFERRED OBSERVERS MASK IAW MEL 35-10-01 CAT AN AUTHORIZATION 002843 IAW MOC 96184 PLACARD INSTALLED.. OBSERVERS SEAT IS CONSIDERED INOPERATIVE. R & R OBSERVER'S OXYGEN MASK IAW AMM 35-11-12. MM02 UPDATED & PLACARD REMOVED. THHIS CLEARS MEL 35-10-01 CONTROL 002843.