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# 7257968 PERFORMED OPERATIONAL TEST OF THE MANUAL RELEASE MECHANISM FOR THE PASSENGER EMERGENCY OXYGEN-SYSTEM MASKS AND NOTICED MASK AT SEAT 26 ABC DID NOT DROP. MAINTENANCE REPACKED O2 MASKS & OPS CHECKED IAW AMM 35-23-00.