It sounds kind of back yardish but try this. Spray about a half a can of WD40 into the horn and rotate it around to get it into the rams horn to the center. Unscrew the adjuster screw and spray in there also. Gently tap the horn with a hammer. Horns normally dont work because the metal contacts under the adjuster screw corrode together and then create a short. This worked on a bad set of horns that I had for my Z11 that were date code correct for the car. Some good tapping, some WD 40 and then hooking them up to 12 volts and they sound loud as new.
I think we should start a new forum section: "Back Yard Tricks" It might net some interesting results.
