Hello canned,
If you type the terms "Pentacon Six repair Berlin" into Google, the very first result that comes up is:
http://home.arcor.de/keinath/Selbstbau/kamerareparatur.htm
The address is:
Kameraservice Ostkreuz Günter Prügel
Neue Bahnhofstraße 6
10245 Berlin
Tel.: 030 / 2913626
It’s about 200 metres from the Ostkreuz S-Bahn station. Nearby you’ll find the Federal Insurance Office for Civil Servants (where you can ask whether your pension will cover the repair), a Protestant district hospital (in case the shock of the bill gets too much) and a cash machine (Sparkasse, for paying for the standard repair).
Regardless of that, I can also highly recommend sending it to Rolf-Dieter Baier in Emmendingen. But I’ve also heard nothing but good things about Mr Prügel so far.
Best regards,
Franz