Dave regarding the horn "button" insert the medallion has a tang that locates it properly in the horn pad, either style wheel/horn pad, it takes some force to get it into the vinyl receiving hole and slot, some spray silicone, or dish detergent solution will help slip it in, start the tang first in the slot and walk your thumb around the edge of the medallion to seat it in
As far as the horn pad itself, do you have the woodgrain wheel?, or the 3 spoke colored wheel with 3 spoke pad with horn ring?
Mike