Years ago I switched from the "welded" belts to seemless O-Rings. They are stronger, grip better, last longer, are inexpensive, and most importantly for me, they don't make a clacking sound every time the seam in the belt hits a pulley. I purchased mine from MSC but any industrial supplier should be able to provide them. As luck would have it, the cheapest belt material worked out to be the best for the lathe application.
david