As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: REF MIC 1658268 DURING OPS CHECK OF MANUAL MASK RELEASE, O2 MASK AT SEAT 26RH FAILED TO DEPLOY. REF AMM 35-23-00-710-001-A. MAINTENANCE PERFORMED OPERATIONAL TEST OF THE PASSENGER OXYGEN SYSTEM IAW AMM 35-23-00-710-001-A.