I have a '77 7700 and an '88 7720. I'm getting ready to rebuild the rasp bars, concaves, and chaffers. As many hours as you have, have you modified anything inside your combines to gain capacityIJ I'm wanting to improve especially the chaffer capacity while I'm doing all this work on them. Do you have any suggestions of things that have worked for you and your dadIJ Thanks for any help, silverdollar