Al Stein

My first guess (assuming nothing from the manufacturer or Sears), there's a gear catalogue called Berg which has all kinds of gears, timing belts, cog wheels, pulleys, drive belts etc. They'd probabbly be able to help if you can descibe what you need.

John C

Find a vacuum cleaner repair shop and take your old belt in. I used a removed beater head drive belt which I cut down in width for a while. It vibrated a bit as it was thicker, and my cutting wasn't true, but it worked until I was able to get a drive belt (several years ago). The vacuum belts usually have more stretch than the Dremel belt, but are plenty sturdy once you get the right length.