ZWO ADC startup positionhttps://www.cloudynights.com/topic/524281-zwo-adc-startup-position/
With the ZWO ADC, you would only very rarely need to rotate it in the focuser due to the extra long and overlapping lever slots in this design.
When you first point it at a planet, place both levers together where the ZWO ADC slot levers overlap, along with the white screw in the rotating scale. Tighten that scale screw just a bit, so that the scale can still be easily rotated when desired with light to moderate drag--- you just don't want it to rotate accidentally. Assuming straight through use, insert it into the focuser and rotate the ADC body until the levers and white scale screw are pointing parallel to the horizon--- if it's an inverting image scope, both levers should be pointing to the left.
Then adjust the levers to correct the planet's dispersion. As the night progresses and the horizon reference requires readjustment, rotate the scale upon the ADC (NOT the ADC itself in the focuser now) until it's white screw is again pointing parallel to the horizon. Then move the levers into the correction position with the gap between the levers centered on the white scale screw.