My husband and I recently went to the quilt show in Hampton, VA, and saw the Martelli rep demonstrating the proper way to cut with a rotary cutter. The nicks (that's we call them) in the blade he said are not really nicks, but kinks from not holding the blade upright while we cut. If the blade is not held so that it is straight up, the blade flexes and will eventually kink. One thing he said we could do to help in this is to stand so that our cutting arm/shoulder is right behind where we are going to cut. Our bodies (if you're right handed) should be to the left side and we should be able to lift our right hand straight up and cut directly in front of it. This helps to ensure that the blade is not on an angle while cutting.