What was found
PASSENGER OXYGEN MASKS INADVERTANTLY DEPLOYED AT CRUISE. PRESSURIZATION WAS NORMAL. ROW 1R PAX O2 MASKS DID NOT DEPLOY. REMOVED & REPLACED PAX O2 CONTAINER AT ROW 1R IAW AIRBUS AMM 35-21-41. ALL CHECKS GOOD. STOWED REMAINING PASSENGER O2 MASKS IAW AIRBUS AMM 35-21-43-550-801-A. ALL CHECKS GOOD. CABIN PRESSURE SWITCH REQUIRES REPLACEMENT PER MX CTL (PRECAUTIONARY). UPON FURTHER INVESTAGATION FOUND THAT ALTITUDE SWITCH REQ'S REPLACEMENT. R&R ALTITUDE SWITCH IAW AMM 35-23-15. PERFORMED FUNCTIONAL TEST OF THE PASSENGER EMEGENCY-OXYGEN SYSTEM IAW AMM 35-23-00. FUNCTIONAL CHECK GOOD.