What was found
CREW O2 LOW, FLIGHT DIVERTED. CREW COMMENTS: NO ECAM HOWEVER DISCOVERING FLIGHT AT CRUISE INDICATING ZERO PRESS. FOUND F/O QUICK DON MASK ASSY LEAKING, INSTALLED SECOND OBSERVERS ASSY AT FIRST OFFICERS, OK TO CONTINUE WITH MEL 2511R AT SECOND OBSERVERS POSITION. REPLACED MASK ASSY. LEAK CHECK GOOD, OPS CHECK GOOD.