It's always nice to find a short series on IMDB, but then it is disappointing if there is missing one episode completely:
The whole series actually is available on Arte.tv, and I am quite sure that they didn't do an owen episode in between. So it looks as on IMDB the Ep. 8 should be Ep. 9 and the "real" 8 (translation from their german title) "Music tells the truth (1973 - 1983)" is completeley missing.
As for me adding data this way is too complicated - especially if as in this case a whole episode is missing - I'd like to know if it will be updated by somebody sooner or later?
The link to Arte (as long as available): https://www.arte.tv/de/videos/113630-008-A/country-music-8-9/