Hello, Edmund, and welcome. I've been participating in this forum for several weeks now. I can't always tell who's a hobbyist (like me) and who's a professional, but everyone has been helpful, kind, or (when the situation called for it) commiserating.
You can buy a replacement roller jewel at Cousins. You'll need to measure the gap in the pallet fork to get the right size. Look up my previous recent posting, in which I learned how to do that. I'm now working up the courage, and looking for the time, to do the impulse jewel implantation. I am told it is challenging.