I've had this pump for a couple of years, only used it a couple of times.
I came to use it last night, but found its got some kind of air-lock as even when not attached to valve, when I pull out the handle, when I let go, it sucks the handle back down.
It does this regardless of whether lever is up or down.
I suspect it was fine before I lent it to someone on a group ride
is it kaput?