Replacing coupling of kitchenaid 5-speed blender - part 2?

I bought the coupling on-line and started to replace it but I'm a little concerned with sticking a screwdriver into one of the motor winding slots to hold it while removing the coupling. What is the chance of damage using this approach? High? Low?

What about a tool for holding the rotor from the top side. The rotor is shaped so that a thin wrench can be used, but I don't know the size or where to buy one. They may be readily available at a hardware store but I havent' gone to look. Any suggestions?