Yay! Something I actually know the answer to, at last…
I had a faulty valve core on my float R, and pretty sure the air valve is the same throughout the range.
You can unscrew just the valve core from the valve body with a standard schraeder valve core removal tool – couple of quid from an auto parts store. If its the valve core that’s the problem then just replace with any schraeder valve core – yes really – I checked with Fox service in the US and its just a plain old schraeder valve core, so one from a car tyre or bike inner tube will do.
If its the valve body (metal barrel the core screws into) thats the problem, there’s a hex key recess in the mouth which you can put an allen key into once you’ve removed the valve core – can’t remember the size, but its imperial not metric (Fox being a US company an’ all). This allows you to unscrew the whole valve assembly from the shock body. Replacement valve assemblies are readily available from Fox.