I stole a piece of copper out of an old stereo, and bent it to rub the back of the hub. Then cut the end to slide into a butt connector. Worked for me.
If this is a common problem I can take it off and get some pics.
It was supposed to come with these little metal round thingies that you connect your stock horn wires to... I actually still have mine from my old DB. If you ever go to the thursday night gathering thing in Union City lmk.