2188 setup for oats with specialty rotor

I have a 2188 rice and soybean special from down south. We use it on soybeans and winter wheat and this year we have a number of acres of oats. We just can't get it to clean to what we think is good
enough. We are getting straw pieces in the tank. Here is what we have and what we have done. Most of this setup works great for winter wheat.

1. Large wire concaves, do not have small wire concaves
2. Installed 4 concave covers to move the material to the back of the rotor
3. Adjusted rotor concaves to thresh a bit easier than wheat
4. Adjusted the rotor speed down from winter wheat
5. Adjusted fan speed all through the range
6. It has knockout fingers installed to help breakup green soybean stalks

This combine is also equipped with one of those air foil screens on the back. It is supposed to bounce the material going out to get the good seed out. It does not have a lower screen like my 1460 did
and in reading up on the air foil, it should not. The oat straw pieces are about 2 to 3 inches long.

Looking for suggestions. I suspect the mill will want a cleaner load after getting the first one on Monday. Is the issue the lack of the lower screen?

Instead of changing concaves on my 1640 CIH rotor machine for oats, I bought a pto pull type machine for $600. Gonna be the 4th year I have used it soon, no problems. Smooth running machine.

A lot of work , but move stationary vanes to forward or fast and remove spikes to minimize straw chopping and maybe remove some of concave filler plates if you have rotor loss.

the type of sieve and chaffer may have alot to do with how clean your sample is

Remove the disrupter fingers and open the concave more. Dry oats thresh relatively easy. Open the concave until you have oats kernels coming out still attached to the straw, then tighten it back up a bit. Can also remove straight bars from the rotor if you have them.