It's half a year since you posted, and I hope you have found help. If you haven't there's a guy called Bob Marshall that makes them. I don't have contact info, but you should be able to find him with a bit of search on the web. There are other sources too; these old industrial Singers are stil in use all over the world even if there is just a fraction of what there once was.

Edit; If your machine takes a V-belt type, you can measure it's circumferance (or measure on the machine with a string). It doesnt' have to be on the millimeter but as long as it fits on the groove you can use any general v-belt made for cars and other machines. They list them with the outer side cirumferance, and if you use a string you will get the inner side, which means add a centimeter or so. The macine setup usually have a good measure of adjusting the position of the motor axle (entire motor usually).

This post was edited by taoseeker on Fri, Jan 30, 15 at 13:54