There is a tool to remove the coupling however KitchenAid does not make it available to the general public. KitchenAid says you must send them your blender and then they charge you a fee to do this operation.
I say, "Bah!"
Follow the instructions below and you will be back to blending things in no time.
To replace the rubber coupling on a KitchenAid blender just follow these four easy steps.
1) Take a sharp knife and surgically dissect the rubber from the aluminum underneath it.
2) Take a pair of Vise-Grips and bend the aluminum wheel off the steel threads. Aluminum
is much softer that steel but use care so you won't damage the steel threads.
3) Screw the new coupler on the shaft COUNTER - CLOCKWISE until it stops.
4) Put the blender bottle on the blender engaging the coupling, fill the bottle with ice and
turn on the blender for a few seconds to tighten the coupling to the shaft.
Jeff
August 2006