Dean, Check to see that hardened washer is inbetween sprocket and bearing lock collar. Be sure sprocket hasn't wore into lock collar. Check number of teeth like Tom suggested. To large of concave clearance and wore cylinder bars will give you feeder beater nightmares. Remember there should be a crown toward middle of rasp and leeding edge should not be to rounded. Bars can be turned if crown isn't wore much past center. If you have solid mounted beater you may want to raise it up as far as it will go in slots. Good luck. Dan