Mariser likes to make smoothies for breakfast. We found the cheapie blenders last about a year before they die. So about 3 years ago, she bought a heavy duty Kitchen Aid Blende. It worked fine untill recently when its drive wheel started losing teeth:
So I bought a replacement from Marbeck. They included the recommend method to remove the old part. It sucks. Basically jam a screwdriver under the wheel to bind the drive shaft and rotate the wheel clockwise until it unscrews. BTW it is left hand screw.
A better way. Get some cheap electrical crimpers and remove the plastic handles. It will now fit under the wheel easily. Squeeze to grip the drive shaft and unscrew the drive wheel: