I have the same problem of my Boxster's horn going off when I downshift, apply the brakes or sometimes when I hit a bump. I would like to check into this idea of the contact points that may be worn beneath the air bag. Could someone send me the pdf on that so I can check that out. I also understand that it may be the horn itself may no longer be properly secured and that a rubber bushing may be worn there. Can someone please send me info or a schematic on how to get to my horn to check that out. Thanks, Ralph