I don't really understand the problem:
It seems to me that all the external parts are M2. I guess the finder is too, and you say that the winding part is M2 too (funny thing to say).
what exactly remains?
the chassis? the metal structure holding everything together?
I wouldn't care If I were in your shoes...
What if you discovered that a small part, a curtain, ring, slow speed mech, whatever has been replaced during a former repair and is not the original?
Seems ok to me as long as you didn't buy a collector item, and payed for such.
If the camera is working good, and it looks good, I would enjoy it and forget about former repairs...
[edit] I see the email. I would ask what is an unreliable chassis. it's not a moving part, so maybe the problems, if there were problems were about tolerances?
I would ask Don or Sherry too about this...