As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING A HEAVY MAINTENANCE CHECK, CABIN ALTITUDE PRESSURE WARNING SWITCH WARNING HORN FAILED TO SOUND WHEN CABIN ALTITUDE AND MASTER WARNING LIGHTS ILLUMINATED. WIRE RING OUT CHECKED GOOD IAW DC10 WDM 213303. REMOVED AND REPLACED AURAL WARNING UNIT IAW DC10 MM 315102. OPS CHECK CABIN ALTITUDE PRESSURE WARNING HORN GOOD IAW DC10 MM 213303.