We have an old banger for running around in, and I need to use my foot
pump more than I'd like on its rather old and rusty wheels.

Lately my pump *seems* (could be wrong) to have become less effective,
i.e. I seem to need more pumps per PSI injected.

Is there any kind of maintenance I could do on the pump? The cylinder
is welded closed, but I wondered what might happen if I (for example)
sprayed WD40 into it via the air intakes. For example would it
revitalise the valve in there? Obviously I could try it, but
maybe someone here has tried it before, and can advise Yes or No!

Cheers
J.