I'm wondering if the rain and snow on our flax is making it hard to get a clean sample. It's a 06, 2388 with an AFX rotor. We set it with the initial settings in the book and it was awful. We've since closed up the bottom sieve, closed concave to 0.2 on the screen in the combine can, turned rotor up to 920 and increased the fan to 650. What else can we do? Increase rotor to 1000?