Thanks, Govert.
I think I remember reading of at least 3 Members changing out the Governor Daphragm. There may be some threads below.
Also at least 2 persons have said the Diaphragm is cheaper from the Dealer then if you buy it from a Bosch Fuel Injection Shop. But, see if you can locate who said that in the threads.
Repair Links
DIY Links by Parts Category - PeachParts Mercedes ShopForum
PeachPartsWiki: Do It Yourself Articles - Mercedes Vehicles