Use small zip ties and close the caps lines. Pour in some cleaning solution in to the caps and cap the heads. That will keep the heads safe and not dry.
Search on here about the warning on how brittle the nipple of the manifold is. always order a couple when changing the dampers. You can do as mike stated or use a paperclamp and clamp below the top or clamp at the waste bottle - one line.
then pour cleaning solvent in the tops. check every day since the dampers are off. slowly slide head to right to lock, may take a few tries.