For the brave ones, as Jeff Alton stated you can buy kits and attempt a rebuild yourself. Two companies I have purchased from are Salvox and CIS-Jetronic. Some are basic with the metal plate and O-rings, others have all the O-rings, shims, and copper washers to refit the fuel lines, even filters.
Good thread on it.
http://forums.pelicanparts.com/porsche-911-technical-forum/272657-cis-fuel-distributer-cleanout-w-pics.html
The filters are very important to keep the system working correctly.
there are quite a few in the system. I would recommend cleaning or replacing them even for those not re-building the fuel distributor due to the age of the systems. The fuel distributor outlet filters can be removed without taking apart the distributor just by removing the hollow bolt to the injector lines. There are many threads on cleaning the screens in the WUR's.
https://youtu.be/0aD7bsj1ASg?si=UOeerN6Hs_qO_pVH
While the ones in the injectors are not serviceable, the cold start valve ones can also be removed and cleaned.
