I have a JD 1910 air tank, 430 bu cart. The rear 200 bu tank will bridge on runs 1 and 6, the outside runs. It only does this with oats and barley, both treated and untreated.the agitator is set on high. Have changed rollers, no difference. Can't figure out why it happens. Static cling? (Poly tank). The bridging is random and my blockage monitor will not detect it because I still have fert going through the system, resulting in misses. There are hundreds of these tanks out there ,I'm sure someone has had this problem. Any help greatly appreciated.