I ended up ordering the polyurethane ones from Poland and they have no slipping issues or noise what so ever. Them being in Poland wasn’t really an issue even though Im from California. I ordered these ones and the shipping was only 4 dollars
https://www.ebay.com/itm/164548045359
The belts can be ordered from
http://kenselectronics.com/ over email/phone. The main belt is square with a length of 9.5 and a wall height of 0.046 and the counter belt is square with a length of 7.2 and a wall height of 0.039. Be patient with the man that handles orders at kenselectronics, he’s a bit old but provides an invaluable service.
I’m happy to announce that the boombox is completely fixed and working great. I listen to it pretty much all day at my new summer job and it somehow sounds way better than the Panasonic 5-cd stereo in the other room. I make drawer inserts if anyone’s wondering.