I just bought a 1680 short shoe with gordon air jet chaffers and I can't keep it from throwing milo over. I've adjusted the fan speed all over and adjusted the bottom sieve. On the info that came with the gordon chaffers it says open the bottom sieve wide open and set the fan speed high but this throws a LOT of grain over. I am running the fan below 600 rpm and just barely creeping through the field and am getting by but it is still throwing some over. I am ready to take them out and replace them with a new chaffer, possibly an adjustable air foil. Any ideas or should I trash these chaffers?