I've found a site that will supply you with the belts you need. Go to electronix.com and click on cd belts in the corner, or search "cd belts" and there are some inexpensive belts to choose from. Square cut will be your best bet. Take your old belt, pinch the two ends together, so it's relaxed, yet protruded. Measure that as you have it on a ruler, with a straw or small pencil looped inside; this way you can estimate the inside diameter.
Get a few belts of each estimated reading within a few tenths of an inch of eachother
to dial in the correct size; they're pretty cheap. Also, it would be a good option to just get one of their belt kits for popular CD player sizes. Size them up to your old belts when you get them. They should be tighter than the old belts by about 10%.
This should help, thanks.
any further questions?