We have two 9870 sts combines set with same beaters, concaves, etc. We have trouble with one machine plugging the Tailings elevator. We have leveled concaves, pulled elevator chain out looked in there to see if the elevator is wore through, checked seives and so on. It works great most of the time just once the straw gets tougher in the evening and going up a slight hill the Tailings slip clutch will go and have to run back there open the door and let it clean itself out. We have replaced the slip clutch to. Just wondering if someone has a brainwave to throw at us. Thanks!