I would replace the tu58 with a laptop running linux
and the the tu-58
emulator. That's what I do with my 730. Works great.
Err... A laptop is a lot harder to maintain than a TU58.
What _I'd_ do is find the diameter of the original roller, use a suitable
O-ring and either glue it to the original hub, or more probably turn down
the original hub, make a sleve to fit over it with a groove for the
O-ring, and put it on with a bit of 'high strength retainer'. This
assumes the entire hub is difficult to reproduce, say because it includes
a tachometer disk.
-tony