Along with what Ray is saying, you can rip a belt in half length ways and get a narrower belt. A cloth belt, that is. I have done this a few times. When you split it it will rip pretty well all the way around and meet where you started. I start the rip with a knife and carefully tear it all the way around. I have some J-flex belts that are narrow and wavy on the edges. They work good too.
Another thing, I take the flat platten off the tooling arm, so that I have slack belt right in front of me. The reason I say this, is because for a long time I worked from the side of the machine ( top or bottom )to use that slack belt. Still do sometimes.
Lin