65 Dart Horn Problems

I agree with slantsix64. Common for folks to change out the copper ring on the back side of the steering wheel. When you remove the retaining ring/canceller (round steel loop looking thing) normally the "rubber" as he called it (really more like a hard silicone that's gray in color) between the retaining ring and the copper horn ring it holds in place is lost. This allows the system to go to ground and honk continuously. The insulation? between the two can be thousands thick but it must be there. Since your steering wheel is off turn it over and check.

I don't see how the turn signal arm screw, which is recessed, can ever contact the copper horn ring. Look at the copper "wheel" that contacts the copper horn ring on the backside of the steering wheel, it's a good half inch above that screw head. Easy way to test theory, put a piece of tape over screw head and replace steering wheel. If horn stops you're right and I'm wrong.