If I recall correctly, pry the cap off the motor's cover. Then remove the nuts holding the motor assembly to the main shaft. To remove the wires, I think you have to unsolder them from the board in the top of the motor's cover. I think you have to do this to change the O-ring anyway. Then as you put the thing back together, you have to adjust the nuts on the rods to adjust the tension on the O-ring.
It has been a while since I did this. So maybe Dave can correct me if I have it wrong.