You have nothing missing just a switch that is been taken apart and improperly put back together. Basically junk. I think someone found a switch and was trying to adapt the wheel center cap to fit it. The standard column only had the switch and 3 screws to bolt it directly to the wheel. The isolation was built into the switch. On a tilt column you had a wave type spring washer that went against the wheel then the switch, then a plastic 3 eared insulator, and then 3 shouldered screws. I will post a 1980 standard wheel with a horn switch for a round center cap. I would give it to you and your horn will work, but your center cap wont fit.