Good luck on this, minxie.
I thought I might be able to help out, because I have a 40-ish year old Concord R to R that I bought on E-Bay a few years ago, on a whim, since it’s similar to one I remember my dad buying in around 1968.
Just checked it out a few minutes ago, but it just spins quickly, as if in Fast Forward, when I hit the Play button, even though the heads move up against the tape. :-(
Hope someone else can be of help!
Mike