This is one of those "I'm not a doctor, but I play one on TV" situations. Here goes... It appears to me that you're over-threshing and loading up the seives. In order to get the berries out of the head, you're running pretty close on the front of the concave, maybe a little too fast on the cylinder speed. If it were my combine, I'd block off the front of the concave by bolting two filler plates under the front bars (part n 273 456 M1). What this does is keep the straw and unthreshed heads in the cylinder just a little longer, allowing you to run the front of the concave a little wider and the cylinder a little slower. That also keeps a lot of the straw from spearing through the concave. The book will tell you to have the back of the concave fairly close. It needs to be closer than that. Tighten it down until it touches, then back off a couple of turns. It should be running as close as possible for wheat. This configuration will allow you to run the front of the concave wider and keep from overthreshing. Stupid as it sounds, run the front part of your top seive fairly open, the back section fairly closed, and the other two according to the book. This tends to blow a lot of the lighter stuff out when it cascades off of the pan, through the fingers, and onto the seive. One last thing is to make sure that you don't have auger flighting extensions on your header auger. If you do, take them off. The flighting should end at the edges of the feederhouse. If they're on there, they tend to bunch the wheat in the center of the concave and make too thick a mat heading into the cylinder. To thresh the thick mat, you have to overthresh the top and bottom, and that loads up the seives. This is way more than two cents worth, but the 860 really is one of the best wheat machines ever made. I used to custom cut with them, and any time they couldn't do a better job than the other brands, I knew it was my fault. Good luck!