You should lock up the flex part to make the cutterbar rigid and more level. To do this it is simple, you take the bolts out of the U shaped hangers, remove the hanger, place it on the bottom side of the leaf spring, and push it back up to the hangers location and reinstall the bolt. This will keep it from flexing, and will be more of a direct cut head. We do this to our 315 flex on our F2 to cut wheat and it works well.
You may want to shine the feather sheets up before you head to the first field. Since the cutterbar is further ahead of the auger, if there is rust on the feather sheets the wheat or oats lay there and don't slide into thr auger.