1 pauls idea - my take on it. we used a brass plumbing cap & cut off the thread portion. drilled and tapped the square area for allen key holding screws. turned contact side on the lathe to achieve a smooth surface for the brush.
2 pic shows alternator brush mounted on a billet bracket that is isolated from the column. the brushes maintain constant contact with the disc as it spins. the horn wire goes down the inner shaft & attaches to the brass. the horn side (hot) attaches to either of the screws on the side of the brushes
3 this shows the small footprint of the mod &shows the brush contacting the brass. tested it and found there is enough contact to power the 12v horn- there are two brushes. the good part is that the disc spins & the brushes are stationary and do not have to swing around. thanks again to paul for his idea.