iPod Classic 160gb 5th Gen won't sync

I have a 160GB iPod Classic that recently stopped synching with iTunes v 12.8. I get the "pinwheel" for about an hour before a message will say that it has to be restored. I do that, tried reloading the iPod with my library and right at the end it decides to dump the music. I've done all the tests and everything apprears to be working on the device. I'm not sure what to do. Help!