I have a problem with a 2003 toro, 36" fixed deck, w/b gear, factory mulch kit and a 15 Kohler. Up until sat I could cut anything at full speed with a perfect cut and no clumping. But now I am getting a strip down the middle on St. Augustine, I am running standards on the bottom and gators on top. All day sat I was trying different combinations. The height is 4.25 its really and yes the blades are sharp. Now the grass is not that thick just 6" tall. I also checked all the belts carefully and there is no glazing, I adjusted them just to be sure there is no slippage. Now get this, when the grass is wet (Downpour) I get a great cut. I'm lost Please help me out here.