Anyone have an old rock tumbler?

So, we went to the North Shore and ended up spending a lot of time sorting rocks on the beaches looking for agates. We found some that MIGHT be agates, but even if they aren't they have lots of interesting colors and patterns. Dug out our old rock tumbler (a 1970's model with obscure origins - probably found at a yard sale years ago). It seemed to work, so we invested in some new coarse grit. After 5 days it was still working, so I ordered some medium grit from Amazon. The next day the motor started making the kinds of noises cars make when they are thinking of throwing a rod, and intermittently stopping and starting. Oh oh. I think it's toast, and certainly not worth fixing. But new ones are expensive. Does anybody have an old one gathering dust in basement or attic that they would be willing to part with?