As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER A TRAINING FLIGHT, IT WAS REPORTED THE STALL WARNING HORN SOUNDED IN LEVEL FLIGHT. ON LANDING APPROACH, TONE CHANGED TO HIGHER PITCH (NORMAL STALL WARNING HORN). WHEN MECHANIC BLEW INTO WING STALL WARNING OPENING, HORN WOULD SOUND. IT ALSO SOUNDED WHEN SUCTION WAS APPLIED. NEW HORN INSTALLED. IT FAILED THE SAME WAY DURING THE FIRST FLIGHT AFTER INSTALLATION.