[Arran]

Yes, I would try to bum a schematic for that thing too, or even buy a folder from someone, it's still cheaper then joining radiomuuuseum. Plus that $25 would be much better spent towards a repro dial glass. AEG was the German equivalent of General Electric so there must be some info on it. The tubes look like nine pin types so they are likely not too hard to find, even American made equivalents.
Regards
Arran