I have just removed the dashboard from my S4 with the intention of refurbishing it.
My first stumbling block is how is the headlight vacuum switch removed from the dash, is it something to with the hole in the bottom of the knob? It looks like is pined, do I need to drill it out?
Mark
Mark, Put the drill away! 
You need to push the plunger in with something, this then allows the knob to slide off the shaft (this was a common method of fitment on older cars).
The chrome bezel then simply unscrews from the body of the switch.
Pure genius, it?s simple when you know how.
Thanks for the help, now back to making sense of my own wiring sketch whilst it?s still reasonably fresh in my head, 
glad I took a few photographs!!
Mark