I don't know anything about canola, but the obvious choices are less air, open cleaning sieve, raise back end of cleaning sieve, redirect air to front of sieve, get a different cleaning sieve, drive slower, grow wimpier canola
How do you have your seives setIJ Sometimes folks close things down too close and then restrict the air to the chaffer. You have to float that junk out on air. Anything you can do to lessen the load of MOG on the chaffer will probably help too. Rotary combines tend to grind up canola stalks. Might even need some blank off plate in the separation grate area.