Check your crank arm bushings. This happened to us and one of the bushings was torn probably causing the shoe to shake apart at the back. Should never happen. I beleive Deere has a problem.
Dale, the material coming thru the Beater Ejector Grate is being carried to the rear by the shaker pan and gets under a vertical cross piece that the grate under the beater is attached to. This material cannot get out of there and builds up until it breaks the rear end of the shaker pan.