Whoa, thanks for all the replies!

Taking bwostosh's suggestion, is there anyone in northeastern Kansas or "close enough" who knows their way around W108s? If I could get someone to come out here who is, I would really, really appreciate it.
Even if I can't though, I'll scour through the one I found as best I can. I found a good inspection guide for them in German (no problem for me to read as I can speak German anyways) and I've been hammering that as well as the section of a Bosch fuel injection troubleshooting book that's dedicated to the D-Jetronic system into my head. Hopefully then I'm reasonably well prepared.

Viele Grüße,
Fritz alias WileeCoyote