I purchased a Timecutter 4220 with a 21 Kohler about four months ago. Since the very first cut, I have had clumping problems. I've tried to eliminate every reason this may be happening: grass is not wet, grass not too high, not cutting too close (I can actually cut the very next day after mowing and I still get piles). I called my dealer and he gave me the stock answer that the grass is too wet. This is not the case. I'm cutting bone dry turf. Any help or suggestion would be GREATLY appreciated.