On mine (which is older and might be a bit different...) the primary adjustment is where the cable attaches to the top of the motor. If you loosen the jam nut, and pull the pin that hold the cable in place, there is a significant amount of vertical adjustment in the position of the motor by turning that fitting and varying the depth of thread in the motor.
I wouldn't adjust the position of the limit switches unless it was clear that was needed, and there was room in the travel of the jack screw to accommodate the change.
