You maybe way past this project already. My 110 has a banjo wheel with a horn ring. Problem I encountered was the gasket that insulated the ring from the grounded hub was basically crumbling. Caused horn to go off in the middle of night and fun stuff like that. Anyway I replaced that gasket with two plumbing gaskets from Home Depot. One is foam like material the other is thinner harder rubber. The combo was perfect for compression feel to engage horn from the ring. My cap was starting to get a crack so I put a thick layer of epoxy on the underside to get some more years out of it.
Foam went on first then rubber. It all comes apart with three screws from the bottom of steering wheel.