Coleen - are you sure it's a new blade? Is it the correct 'brand'? I know that some of the blades have a notch in them and some don't. Not all brands are interchangeable. Also, is it possible that you put the center screw on the correct side? Did you tighten it too much (which would keep the blade from turning properly)? I've accidentally put my cutter together wrong and it will act up - there's definitely a right and a wrong side for the screw and nut.

Okay - suggestion? Take a wad of aluminum foil and run the cutter through several times - if there's a nick or barb on the new blade this should be enough to remove it.

When all else fails, throw it out the window and buy a new rotary cutter.