Count teeth on sprocket on left side of cylinder. 18 is std. Options 25, 30, 35. The more teeth the faster the beater. Beater will crack beans if running to fast for conditions. Reasons for options is you may need to run beater faster for the greener conditions. Also zero out the concave. Many concaves were not sitting in machine square because mount for thresher housing welded in out of position. To check this you best pull out the thresher beater and with concave zeroed at front it should be zero in back. Good luck