Originally Posted by
exxongraftek
eBay has some, in fact I'll be selling a few out there soon. These are known for cracking, I'm replacing the ones from my rider bikes with the alloy sealed bearing ones - which are cheaper than the originals on eBay right now. Go figure...
...indeed they are, I have a handful of them that are so cracked. The seem to continue working fine that way, but your alloy sealed bearing ones is the most practical solution, which I do sometimes as well. There used to be some Shimano pulley wheels you could pull off scrap derailleurs at the co-op that would fit, but the whole thing is pretty hit and miss.