I had a few minutes yesterday & sat down with that wiring diagram yesterday.....OMG.....we really need to know what is going on inside that servo

Following the comments in Red is the simplest way. Verify the positive & negative voltages that switch are available @ the relay. You can hear them click & you have verified they are good, so if the voltages are their you probably know the answer.
The actuator isn't bad price wise $192.00cdn