I would find another machine to harvest it from. Are you sure the part is bad?
No affiliation...
https://www.ebay.com/itm/295853421181
You took on a heck of a project recapping that thing! I want to do mine but I'm afraid! LOL
So, you are in Portugal? I think I bought an OEM rubber kit for mine from a guy in Portugal. It had the belts, idler, pinch roller, and back tension band. I wish he had more!