if you replace the concave, replace the concave angle as well. you can get it from abilene machine lots less than from deere. i went back with a st. john's weldeing concave and its been great ive cut approx 4000 acres of milo since the install and it looks brand new. one other suggestion is look into putting half sprockets on your feeder's rear shaft. i didnt do this but i saw them somewhere on the net after i replaced mine. the next go around on replacing them would be lots easier since you could just unbolt the sprockets and take each half off and put new ones on. would save lots of time on removing the feeder and having to take them off they way you usually do.