Thanks w8ye. With a piece of tubing connected to the "IN" side I can blow air through the pump. If I cover the "OUT" fitting with my finger I cannot blow any air through it, so it doesn't seem to have an internal leak. I can also hear something clicking inside the pump which I assume is the diaphragm (or reed).

I can just barely blow air through in the reverse direction.

proptop, I will try your test, too.

David