Wild Bill -- thanks for the reference. Per the wear at the base of elephant ears -- My guess would be that material from the Shelbourne head (basically very small components in relation to operating other heads) is released sooner by the vane transits and is dropping toward the rear of the impellers rather than being carried fully into the threshing area by the vanes. At the rear of the impellers there's basically no curvature to hold smaller stuff against the skin of the cone. All impellers do this to some extent, but ears will wear sooner with a Shelbourne. Actually, 500 hrs. is about average time for replacement of OEM impellers. HOpe this is reasonably clear.
