I decided to take apart a Bontrager reCharger floor pump recently on a whim, one of those whims during which you pay no attention at all to what you're doing. After putting it back together, the pump now admits air so that when connected to a full tyre the handle goes all the way up by itself.
Looking both here and at manufacturers making more serviceable models reveals the existence of one-way check valves within the pump itself to prevent air escaping from the tyre. Never thought about this and had always assumed it was either handled by the inner tube valve or some magic in the pump connector.
What do these check valves look like and where are they typically in a pump? If anyone knows the answer to this specifically for the Bontrager reCharger, or would be willing to spend two minutes taking theirs apart more carefully than I did to look, then that would also be very useful. I have a feeling something went boing and I'll find it under a skirting board in a few years time.
There are also some genius solutions out there which I might have to try.