After not using my MDS-JE780 for awhile, I left an MD in the player and forgot to take it out. It wouldn’t eject and freaked out. This thread helped a lot. Thank you posting this. I started looking for the belt on the internet and seeing what else can work and measuring the diameter. Then I started looking at these Rainbow Looms that you can make those bracelets out of that my daughter has. They’re a bit smaller but I figured I’d try it out. I worked it through the pulleys and it worked! After going through several MDs it’s been playing fine and ejecting with no issues. Here is a picture of the rainbow loom versus the belt that came out of my MDS-JE780. Here is a link to the rainbow loom: https://www.amazon.com/Rainbow-Loom-Crafting-Metal-Rubber/dp/B00DMC6KAC If the belt\rubber band is too tight will that damage the pulley? Now I have to figure out why my MZ-R900 skips after 10 minutes of play.