I had the same thing happen to me with Olfa blades. I knew it wasn't the blades because I used some out of the same package. I had 2 blades in one cutter, another one I had put the little curved piece in backwards. I've also over tightened the screw a few times and they don't work well when that happens. I've found if I'm cutting a lot of fabric I need to take the cutter apart and clean out the lint.