Are your snapper rolls working properly, or are you getting material wrapping around themIJ We had an older 6 row head that the snapper rolls were worn. The knife (under the rolls) was not cutting material off of them to stop wrapping. This also lead to the problem you are mentioning. In the worst cases the rolls would stop and the clutch would slip. Once we readjusted the knifes, it took care of the problem. We also found that moving faster helped, especially in thinner areas. We also noticed the problem only in certain varieties.