As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RUBBER RING ON SEAT CARRIER COMPRESSED BEYOND LIMITS SUCH THAT WHEN BLAST-VALVE HANDLE WAS AT REST (NOT ACTIVATED), THE SEAT CARRIER WAS NOT ABLE TO PRODUCE A SEAL WITH MAIN VALVE BLOCK. SUSPECT SEAT CARRIER WAS NOT THICK ENOUGH OR VALVE-WEAR-PAD WAS TOO THICK.