I am The Disrupter Guy and I also rebuild concaves and cylinder bars. I would guess that you have more then 1500 hours on your concave. Square edges on concave bars restrict the flow and force grain to rub on grain. A rebuilt or new concave will take card of your trash in your sample. I also think that you are breaking up your cobs in your concave area because if your concave has rounded edges you have to set the concave tighter to get it to thrash and this is what is breaking your cobs. Im not saying that The Disrupter lugs don't break cobs, they do, but in most cases we don't have a problem. Call me any time at Estes Mfg. Co. ask for Don 1-800-235-4461