I bought a new JD 1770 12 row planter this spring and the left side of the planter was planting 5 to 10 % less than the right side. This really showed up in the beans. There is only one seed drive to do the whole planter so it cant be that and one vaccum system. I cant seem to find any leaks in the vacuum tube but that must be what it is? anyone else see that with 12 row planters?