The wiper arms (not blades) are splined. If you remove the arm you should be able to move them one spline to keep them from hitting. The arms are often stuck on from the arms corroding and slightly bonding to the shaft. I was able to get mine off with a battery terminal puller (does anybody even know what those things are anymore?). Use some anti-sieze on the splines and next time they will be easier to remove.
