Thanks Jules!

According to the wiring diagram there are 4 wires going from the switch to the motor: brown, red, dark green, dark blue.

Can you tell me which wires should have power when the switch is in park (off), speed 1, 2, 3?

I understand that the switch does not turn off the motor (when working correctly) but mine does. That either means the switch cuts all power to the motor or it is a ground issue. I doubt that it's the gear inside the motor because if it was the motor would still go on even in off position.