We have the the original smooth bars on and they are in the retracted position. Yesterday I spoke with a mechanic who suggested placing a tined grate at the top of the stone trap to help keep material moving threw. I had to build one and it seemed to help when I tried it later. long strands of twitch grass seemed to be starting the wrapping. Maybe the grate keeps it from bunching in stone trap area and then the beater grabbing and pulling it all the way around. Thanks for your suggestion, Terry