my name is Hugo an i live in Portugal
sorry for posting in English (i cannot speak or write German)
i am posting here to show you some tecniques i use to repair broken bakelite radios and i hope it is usefull to someone or if you have anymore tips i appreciate it.
the guys on the tube tv section were very helpfull when i was repairing a philips tv so here is my contribute to this forum

so first step remove the chassis , speaker etc next i go to a scrap radio and cut a piece of bakelite to match the shape of the missing piece
then i grind a bevel around the patch piece in order to accept a lot of epoxy glue
mix the epoxy and glue the piece
make sure to leave the patch half milimeter low in order to accept a layer of filler to be continued