I solicited some information from "eyeball" a few weeks ago concerning my satisfaction with Marlin's impellers. No one has yet answered my reply or my concerns. My concern was that in doing downed wheat I get "surge" feeding. The straw windrow behind my machine (2166) is actually a little piles of straw about 6 - 8 feet apart as a result of the "bunch feeding". Anyone know what would cause this? My feeder chain is adjusted per operators manual.