Can anyone tell me where I can get a replacement belt for a Sony WM-EX5?

DocP is the man for belts alright. I think the belt is between 8-8.2 inch. I recently sold an EX-5 on eBay, but the buyer says it is not working correctly. He's a genuine buyer, so I don't doubt him. It's most definitely a belt as he can hear the motor whirring. I tested it some time back and it worked perfectly, but the belt must have stretched since.