As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING C CHECK INSPECTION AND FUNCTIONAL TEST, THE CABIN PRESSURE SWITCH (16WR) FAILED TO DROP THE OXYGEN MASKS. MAINTENANCE REMOVED AND REPLACED THE CABIN PRESSURE SWITCH (16WR) IN ACCORDANCE WITH THE REQUIREMENTS OF AMM 35-23-15-400-001. FOLLOWING ITS INSTALLATION AND INSPECTION IT WAS TESTED AND FOUND OKAY.