I realize that there were indeed a number of different cylinder phonograph friction disc diameter sizes with various governor spring variations (3 governor spring, 4 governor spring). The Columbia aluminum friction discs seem to be the most susceptible to having a warp so I was thinking that replacing those discs would be the initial focus. Brass friction discs seem to have survived only slightly better than aluminum relative to being warped but amazingly there are quite a few brass originals that still spin perfectly true and thereby support a nice, steady, natural playing cylinder. Even a few aluminum originals have survived pretty well but not that many.
I suppose it was wishful thinking when I created this post since warped governor friction discs (on cylinder machines) are surely a pretty common problem. I had hoped to generate some feedback which I have and it's appreciated.
Goodness knows there are lots and lots of cylinder phonographs out there besides some of my own that play with even a slight flutter due to these warped friction discs. Since original friction discs are fairly thin one must be mindful of truing them up on a lathe if that is the chosen option. Most of mine have only a slight warp and truing them on a lathe is likely possible but I'm sure there are plenty of discs out there that have a more severe warp and/or even (yikes!!) a slightly bent friction disc shaft which would be a REAL problem.
Doug