Originally Posted by
Cpt.America
yep.. even when unlocked, it's on there like it IS locked. You have to be careful to only press it on enough to make a seal. Anything more, and it becomes a pain to get off. The replacement tube's valve was NOT threaded, and the pump head goes over and comes off with ease.
You could try lubricating the sealing collar inside the pump head just prior to use. I'm guessing it's a rubber O-ring type thing. If it's dry it will be a pain to go on and off. On military radio/headset cables, we always wipe some spit on the connectors' rubber o-rings or they will simply not go on at all.
Coincidentally, my pump has the opposite problem. Works fine on threaded valve stems, but on the non-threaded ones you have to make sure it's pushed all the way down. If it's not, it will slide off during pumping once pressure is above 100psi.