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The diverter valve (aka shutoff valve, check valve, etc) can be taken off the head with one screw. Twist it out of the head while pulling up and don't pry it sideways, since it has a tubular extension that goes into the head. And it can be taken apart into two pieces by removing two Philips head screws. Basically, just clean it with carb cleaner or similar cleaner until passages are cleaned up and the vacuum valve is working (and membrane is intact and air tight) when vacuum is applied. Vacuum can be applied manually with a hand vacuum (like those used with vacuum brake change kits) or with a Mityvac oil changer (manual pump). Some say you can open the valve with your lungs, but that didn't work for me (the Mityvac oil changer worked for me -- took about 5 pumps to open my old valves). Also, of course, you should just search the forum(s) with P0410 and read more.
It's possible that the passages in the head are clogged also. Be careful about putting oily stuff into these passages (like WD40, etc and maybe some of the cleaners), as if too much gets in and goes to the catalytic converter, which it will because these passages go directly to the exhaust manifold, it can destroy your very expensive cat converter.
I will paste a picture below of a shutoff/check valve that has similar structure to many of the Mercedes valves like those on the W210 and other models. I think the dark gray and light gray parts are what can be separated when you remove the two Philips head screws.
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
