I was watching a 1972 West German documentary on the GDR, when I heard a groovy track named "Danke, Weitermachen" in the background. Bizarre socialist lyrics, but otherwise seriously good music. I only couldn't find out the artist. Anyway, do you happen to know more tracks of this kind?
I didn't embed the video as the time code didn't work that way.
There's also a very promising-looking compilation of GDR grooves, pity there aren't any sound samples (which is common for the less mainstream stuff, though):