We are having a problem in shelling corn above 2 mph. When we try to speed up the combine the combine wants to throw the corn out the back over the screen. Our nieghbor has a combine identical to ours and he can shell about 3 mph with no problem. The only diffrence between the settings is that we pulled our cookie sheet out from the very bottom of the shoe. Could it be possible that we are lossing to much air off the fan or does anyone else have any suggetions