I guess the first thing I do is pull into the row and pick for a little ways and then stop and shut off the machine. Then you will be able to see if you have corn loss from butt shelling in the head, or if you have a piece of metal worn through creating a leak. If all checks out OK under the machine, then you can figure you are loosing grain out the back some how. If your grain loss sensors are working, you should have an idea about which place to start looking.
If you suspect shoe loss, you can open the chaffer (top screen) enough that you can be assured you won't loose kernels. Pick a couple hundred feet and check again. You have enough shoe with a '66 to handle a lot of corn, so I would say your loss is rotor, but I like to rule out the sieves first.
If you suspect rotor loss, there are a few variables that play into the equation. Most CIH heads will not run as much fodder though as other brands, but if the stalks are damp you will have more trouble getting the grain separated out. If you are running damp stuff through, more rotor speed and more concave clearance would be a place to start. However, never adjust more than one thing at a time. That way you know what is doing what when you make your adjustments.
Sometimes in this big of crop, it is necessary to pull out every other wire in the concave to get more grain out early. If you have a grain concave (smaller wires, closer together) I can about guarantee you will have to pull out wires.
This should give you a place to start in your sleuthing. Good luck!
Thanks for that, and i have done all you suggest. If i had to guess, i would imagine that the kernals on the ground (its just a few, maybe a bushel or two/acre) are simply caught up in the fodder exiting the rotor.
So pulling wires makes sense, but i have never done this. How does one do that, and where? I have the large wire concaves (all 3 section identical) and keystock grates.
Sorry for the delay, my computer wouldn't log in.
When you remove the wires you give the grain a heads up chance to get out of the cage early on. I would remove every other wire in the first two concaves and see how you get along. Make sure you plug the wire holes with bolts and lock nuts or you will get all sorts of MOG stuck in the holes. Good luck