Your walker loss is directly related to your concaves and cylinder bar clearance and condition. If your concaves are bellied out or worn, there is no way to keep the wheat off the walkers. You must use the back draw bolts to level and tighten the concaves. You must strive for almost zero clearance between concaves and cylinder bars. You cannot separate the wheat if it is not down on the separator. The walkers are merely a means to remove the straw from the combine, they are not a separating device. I am constantly amazed by the number of JD owners who do not understand the simple mechanics of harvesting.