Install extra channel iron under auger to act as another stripper and prevents overload of rear stripper. 400's have this stipper. Widen opening to feed chain but that could posiblly aggrivate feed chain plugging. You see the 4" flighting does not even bring the straw beyond the header fillers if they are installed. If feed is plugging to EZ check back in. Bring filler inbetween header floor and feeder floor as close as possible and knock down flush if needed. If feed chain slats are rounded bad you may want to square them up again. 2" flighting extentions may help if you don't have them installed. 4" flighting all the way to the center line of finger area has made our older headers very hungry in wheat or barley straw. Be sure stainless plate under feed chain is not wore threw. Good luck.