[Closed] Help with Innovations "Top Dog" track pump!

I have an innovations top dog bike pump that has been great for the last 5yrs but I now have a problem with it. Which is that when I connect the pump to a semi-inflated presta tyre, firstly the pressure on the gauge reads zero (it use to immeadiately give the tube pressure). Secondly if I then pump, initially some air is going in, until gradually the handle rises on its own and gets v hard to inflalte until it reaches 25psi, which seems to be the max I can get in any tyre, road or mtb. Ive tried a new hose + head adapter with no effect. I assume there should be a one-way valve between the pump cylinder/piston and the gauge/pump valve? So when you attach the pump to the tyre, the adapter just depresses the presta valve so its permanently open and the gauge reads the pressure, but the one way valve stops any air getting to the pump cylinder(and so stops the pump handle rising up). Then when you pump air just passes through the one way valve to the gauge and tyre.

There is a plastic connector with three o-rings, in the right place, but there seems to be no one-way valve associated with it, just a straight through hole! Cant see how the valve could have just dissapeared! Any ideas, I'd love to get it going again.

Cheers...