I have heard of differences and have noted balance wheels in parts lists with a couple different size pulleys. It appears according to
http://vssmb.blogspot.com/2011/07/lo...andwheels.html that one may have to switch out the bushing as they both fit on the same shaft. I don't know if Rain ever did a tutorial on removing the bushing. Fortunately, for me, I have a brother that has the tools and know-how to do it. He recently removed the broken bushing from my Junker & Ruh and repaired it so that it works.
Janey - Neat people never make the exciting discoveries I do.