My 91 300D 2.5 Turbo runs *too* well! That is, it is so enthusiastic it runs on after I turn it off with the key.

Searching the site I realize that the problem is probably a leaky diphram in the shut-off mechanism. The red shut-off lever moves, but it stops a few cm short of activating the shut-off correctly. When I nudge it down just a little more, the engine shuts down promptly.

As everything else vacuum-related works just fine, I figure I just need to have either the diaphram or the whole solenoid replaced. The CD doesn't seem to explain how to do this, and a previous post said "The part is about $19.00, but it can be tricky to replace". The question is, *how* tricky?

I see that inviting bolt head on top of the shut-off solenoid, but it has yellow paint over it (DIY beware?).

What are the steps involved in replacing the offending critter?