About 4 moths ago I purchased a new 4220 Timecutter Z with a 21 kohler. Since the very first cut, I have had problems with clumping. I've tried to eliminate every possible cause but now I'm just plain frustrated. The grass is not too wet (this is what the dealer told me the problem was) as I have cut bone dry turf with no rain for several days. It's not too low (highest setting possible). Grass is not too high ( I can cut the very next day after mowing and will get the same results). It almost looks like the grass is getting hung up in the deck and not being discharged. I will get the clumps midway through a row but mostly when I slow to turn. I'm cutting mainly fescue in the St. Louis area. Cant figure it out...love the machine but cant take having to double cut AND go behind with a blower every time I cut to get rid of the grass piles. Any advice would be greatly appreciated.