I bought a yerf dog kart used from a buddy of mine for my kids to ride. I bought a new speing and 6 new insert buttons for the t/c. We've been able to ride the kart a few times without any issues. Went to ride yesterday and noticed that it was running fairly slow. Looked back i noticed that the belt was only half way up the driver and not moving any further (throttle all the way open). Stopped the kart and noticed that the "peaks" of the driven unit were sitting in between the insert buttons. Dont know if this this is worn out or what. Ant ideas? Thanks.