A motorized pump is probably more hassle than it's worth. A MityVac is just a pistol-grip thing that sucks on a hose; its barely more complicated than a turkey baster.

Using a clean piece of vacuum hose, try to blow through the valve. You don't need all kinds of pressure. It's either open (you can blow through) or closed (cannot blow through). When you apply power & it clicks, it should change to the opposite (open vs. closed).