The coupler has a reverse thread, so it has to turn clockwise to loosen it. To stop the rotation, I put a blade screw driver through the propeller blades in the motor. Then, I drilled 2 shallow holes through the coupler only, and used these as the 'keyhole' for my needle nose pliers. Twisting the pliers clockwise, it came loose. (NOTE: The coupler has a metal base below the rubber, so you need a drill bit that will go through metal. You may have to scrape off the rubber on top.)
Susan, June 2007