Wouter,
if you do a Google with 'compur rapid' and 'repair', you would come up with links like this:

http://manuals4less.com/shutters.htm

where you can get a booklet for the rapid shutter for $10

which on the one hand is a rip off, but on the other would be a great help. We bought a copy of a Linhof 220 exploded view for $25 some place else, but it was well worth it.

Or try here:

http://rick_oleson.tripod.com/index-88.html

but rick discusses the compur shutter only, not the rapid kind! Still, it might be useful.

Good luck!
the medform-norm team