I have quite an old handpump that fits on my frame.
It looks like it's called TOPEAK "miniDUALG - optimised for MTB/ROAD."
It has a pressure guage and various bits that screw the handle to the body and the body to the end with the pressure/bar valve, with an interchangeable head that allows you to switch between Schrader and Presta / Woods/Dunlop valves.
Last night, when I got a puncture, it wasn't working. The pump was placing as much resistance to pumping in as pulling out (I may even have been drawing air back out of the tyre, I can't remember). Somewhere, there must be a blockage which is stopping the one-way valve from working.
But where is the air intake for the pump anyway? In the head (part of the valve adaptor), the middle (it has two sets of o-rings, with some cleverly designed stuff between them), or the handle (which has gaps in the screw thread down which air might flow from the outside — if that cup-shaped head seal would let it).
Anyone got any suggestions? I'm baffled - but I don't want to throw away a perfectly good bike pump if I can repair it.