I've got two i14Ts, and the pumps are VERY different. One runs quite smoothly up and down, and the other one seems to bind in the barrel, almost like the piston is out of round or the barrel is. They've not been used all that much (maybe a couple dozen times each), and I thought the sticky one would "break in", but it hasn't. They both "pump" ok, but on the sticky one, it is a lot harder to do the "pull" stroke. Almost like the one way valve in the piston (assuming that's how it works) isn't opening.
I was wondering if I should take it apart and compare them.. There's two screws holding the cap (through which the pump rod travels) in place, so I figure it's reasonably easy to reassemble.