I use a tow behind ground driven metering system flexicoil 2320 air seeder behind a caseih pd500 air drill. I get a bunched or wavy seed pattern behind the drill. Even across the width of the drill, but high density for about 10’ of seed row and low density for about the same distance. When the crop emerges it looks wavy. Why is this? Is something wrong with my metering system? Is it air related? Thanks for your input.