Good book for German pen repair?

[amk]

I've been repairing various lever and button filler pens, and I'm moving on to piston fillers.

But piston fillers don't seem to be terribly well covered in the wonderful Marshall & Oldfield book. I'm wondering if there is a book available specifically on German piston fillers - OK, it may well be in German which will make me brush up my rather rusty language skills.

I'm okay when I'm working on Pelikans, but I find that every other piston filler seems to have its own different system. Even knowing which end to open first would be a help! I've been able to get on with a few Ero and Senator pens, but sone of the other brands have completely defeated me.

[whych]

I haven't found anything for German pens. The problem is that other than Pelikan and MB, most of the other pen makers were overlooked.
If you have a problem with a particular pen, pm me and I can see if I can help.