A Singer Graflex maybe?

Win (Wyn) did a couple of "Black Folk Music in America" 35mm filmstrips for Singer Education & Training Products. The panels were cued to soundtracks that came in LP (7" & 12") & later on cassette.

The sub-division was based in Chicago and the 70s timing is about right. Don't recall Jenkins or Clemmens doing the same but a lot of stuff was uncredited.