its a blaster 98, the rubber wheel the chain rolls over right behind the small sprocket keep getting chewed up by the chain I put a new one on and within the first hour of riding the chain will start rattling from rubbing the post(cause it ate up the rubber guide) what would cause the chain to tear this wheel up, the rubber wheel rolls freely around the post, the chain is tight with about an inch to an inch and a quarter of play(the chain does'nt come off on its own when this happens). any ideas, anyone even seen this happen before?

 

You have the chain over the top and not the bottom of the rubber wheel, right?