[slotloco]

Yes, the same issue remains that there is play in the swinging arm, and the vertical height screw is also not centred. 
I have (and use) an RSM-3 myself, but only for doing plastic wheels one at a time. Most guys in our club have one of RSM, Professor Motor, and the odd predecessor - the Tyre True in this vein. I don't think anyone in our mottley crew has a Tire Razor, as they were only imported briefly by a guy who didn't stay in the hobby long as a supplier.
Actually a couple of guys made their own lathes too.... not sure if they are still using them. 

But going carefully one wheel at a time, guys in our club get their tyres as good as mine, and I have all the tools and (most of the) time in the book.

We also have a gun engineer in club, who also is good with CAD and has an Endor 5 pro. I think he is currently tossing up between 3D printing a Hudy lookalike that is available for download, or creating his own lathe from scratch.
I wonder if anyone here has printed up and is using any of these.