I scrawled open/close arrows on the headstock as I was forever forgetting the direction.I usually put a bit of timber through the chuck jaws onto the bed & then haul on the big c spanner, I dont like clouting things with a hammer lest i break teeth in the headstock. The nut on the Harrison is counter intuitive in that its captive on the spindle & undo's by pulling it upwards from the front.
Put a bed protector made from timber over the bed so you dont drop the chuck on it.