Might depend on how bad all the rollers are. That white one I believe is replaceable through RT Specialties, not so sure about the two that ride inside the metal part.
What's not shown in the photo above is the chunk missing from the roller on the other side. I didn't see any rollers that look like this one at RT Specialties (it has a ball on the end). Would I press off the roller and press on the new one?
I think that's what you're supposed to do. They have one roller that says it's a press on, and I was pretty sure it was that one since I ordered it by mistake. You could call them and double check.