The OL is a thermal overload switch that will open if the motor is overloaded. It should self-reset when the motor cools but apparently yours has failed or the internal wiring to it has failed. You should normally have continuity between M1 and M2. You could apply your test cable across M2 and M6 for high speed operation and M2 and M5 for low speed operation. Of course, you must also apply power to the start winding between M3 and M7. Iv'e had a couple of these motors apart but don't recall any specific info on the overload switch.