As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ALT. AIR KNOB BECOMES LOOSE AND INOPERATIVE WITH USE. KNOB IS PLASTIC WITH A HELI-COIL INSERT, SCREWED ONTO THREADED END OF CABLE. KNOB MUST BE ROTATED TO OPERATE ALTERNATE AIR AND THIS CAUSES KNOB TO WEAR AND LOOSEN ON CABLE END. A MORE SECURE METHOD OF ATTACHING KNOB TO CABLE SHOULD BE TRIED. PERHAPS A SET SCREW OR ROLL PIN.