I use the popular 2.2KW water cooled spindle moved by a 1610 ballscrew which does fall slowly under it's own weight when the stepper motor power is removed. Part of my SOP is to put a prop under the Z axis before powering down the control box and removing it again after power is back on. It's not really a problem and I would expect to re-home after an e-stop anyway. No water leaks so far either.