I know I'm not the only one who's had issues with their kite pump bleeding pressure. Simon at Milang fixed it mine in a couple of minutes and might be helpful to share....
The problem is the interior plastic shaft pipe (inside the metal shaft) is too short. Unscrew the base disc (mine was pretty tight), pull out the plastic shaft pipe, cut a piece of garden hose 1cm longer than the plastic shaft pipe and push back up the metal shaft. Screw the base back on but make sure its covering the bottom valve. Test it by pumping it with your thumb over the end and it shouldn't leak air.

Sorted.