We have a 1250 planter that at times have trouble starving row units with seed. Big seed seems to cause more trouble as well as planting faster. Added speed tube last year so ran into it more last year, but had trouble from time to time before we added speed tube. If I up the air pressure it gets it to the outside but then starves the middle and visa versa. Run talc graphite. From what I understand 1255 planters improved upon this? Anybody have a tips to help with this issue?