Cleaning out the garage, I found an old mid-1990's Avenir AirMax pump which never worked right. I think the problem is that the check valve inside the pump body, is missing. (The pump delivers air, but the gauge doesn't hold a reading, and the handle will fly up into your face if you let it go.)
This check valve is a replaceable item in a Silca pump:
Avenir is just a brand name owned by Raleigh now, so there's no help available there.
I hate to throw the pump away, it's all steel and all but unused. Just need to find a check valve. Any idea where I might find this obscure part?