Ran a 1688 for 14 years in spring wheat , durum, barley, oats, flax, canola, and oil sunflowers. Tried cover plates in all crops but only was satisfied with there use in sunflowers and just on the seperator grates. I didn't enjoy changing concaves throughout the season, but felt that is one of the bonuses of a rotor machine. You can tailor it to the crop your harvesting. Biggest problem I found is that they limited capacity. You had to slow down in order to maintain acceptable rotor losses.
Seemed to have best luck running narrows for wheat , canola and flax. Narrow, wide, wide for oats, barley . Narrow, wide, wide with covers over seperator grates in oil sunflowers. Sometimes tried different combinations in sunflowers depending on how dry they were(breaking up too much). Always kept slotted seperator grates in.
Not sure how harvest services concaves differ. Maybe cover plates will work for you. Just my $.02.
Seemed to have best luck running narrows for wheat , canola and flax. Narrow, wide, wide for oats, barley . Narrow, wide, wide with covers over seperator grates in oil sunflowers. Sometimes tried different combinations in sunflowers depending on how dry they were(breaking up too much). Always kept slotted seperator grates in.
Not sure how harvest services concaves differ. Maybe cover plates will work for you. Just my $.02.