What happens when an egr valve malfunctions? Is that the same as it being blocked?

If I remove it, it appears that I would have to get rid of a bunch of soot build up in the manifold. I am a decent maintenance DIY guy, but just don't have the time to tackle something like this. A shop would probably be very resistant to something like this, right?

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Alan Hamm
'87 300SDL 277K Miles
'89 560 SL 68K Miles