The blades are hitting the ends of two of the blades but does not hit the mower deck. The blades must be slipping but still should not hit each other i would not think. I ground down the ends of the blades a little on all ends to make them work and also ground the paint off around the bolt holes so they would not slip. I have tried to contact the place where i bought the blades but they have not contacted me back. I am just confused why all of the aftermarket blades say it should be 20 1/2 inch blades and would think a lot more people would have the same issue?:confused2: