Been having trouble using an airfoil seive in flax. Combine is a 1480, with crossflow fan, and I haven't been able to use the airfoil in flax, usually had to resort to swapping in the original equipment chaffer, which works fine. I like the airfoil for the capacity it offers in all other crops and changing it isn't so much the hassle, it is the monitors and such that are kind of a pain. Any thoughts as to what I might be doing wrong? If I increase the wind to the point where chaff floats out, so do seeds in large volumes. Wind less than this just doesn't do a clean job, and usually plugs return, which tells me that I need more wind.... It's quite puzzling. The Peterson chaffer in the other 1480 with standard fan works like a charm. Any ideas?