W126 Ignition switch turns, but no start detent or spring back

[AUDIBLE]

1987 300SDL

Everything else is fine; no stuck key, etc. Key inserts fine, turns fine and all idiot lights, accessories, etc. work the right way. Just no pressure against the key in the start position, no 12 volts going to the solenoid, and no key spring-back. With the key in the normal "run" position, one position counter-clockwise from "start," the starter can be hot-wired and the car runs fine.

I've read a lot of threads about pulling bad tumblers, etc., but want to know what the problem here really consists of, and what needs to be replaced.

thanks!

I found a thread that seemed to be about this, but there was a lot of shorthand in it that I didn't really understand.
so my ignition switch quit working