I have a RT8S tiller and have the same problem. I believe once you set the tiller up on it's nose you can see how the belt is routed. the drive belt comes down from the top and goes under the mail pully connected to the motor. I believe it goes up on to the right of two small pullies. Because there is a rod that keeps the belt on the right pully, the pully needs to be un-bolted, so the belt will go under the rod and the belt is slipped on the pully, and the pully rebolted to the frame. Once this is done the belt goes under the left small pully before it goes back on top. Depending on which direction you want the tines to turn the belt goes over or under the small pully before it goes around the larger pully.
Hope this helps. if you get better information for the belt routinf on a RT8S tiller please post it here
Jack Frazier, May 2010
