Looking at this diaphragm from Ebay, the shims and everything you speak of are behind the diaphragm, within the IP?

Mercedes Diesel Injection Pump Diaphragm 190D 200D 220D 240D 300D 406D 1963 79 | eBay

So I would have to remove an additional housing which keeps the diaphragm in place?

Looking at the first photo, that would entail removing the housing with the straight edge screws.

Sorry about being anal, just want to make sure I got it correct.

Thanks,

Dwayne