I'll be buggered if I can find a bloody valve.

Unscrew gromit at the top of one of the stanchions. It's like a plastic hex bolt

As above, right stanchion I think

Right stanchion has a rubber bung in the top with a hex bolt underneath. I unscrewed it bit there's nothing underneath.

Is that the MX LO from Wiggle or does it say MX Pro Lo? The Wiggle ones were coil sprung so no air valve. Under that rubber cap You'll have an preload adjuster.

I thought they were coil too. Well the one I had was.

The one I got from Wiggle was coil too. But it was a Mx Lo according to the stickers. I also bought a new Mx Pro Lo from here and it had an air spring but it had Mx Pro Lo on the decals. I think all Mx Pro Lo are air… Still the coil spring is not a bad thing, less to worry about. But the preload adjustment didn't make much difference so if you are lighter/heavier than a average rider than You might be looking at buying a new spring.

Ah, MX LO. That would explain it then. New spring for the big lad.

Depends whether You can get a new spring for it and how much will it be 🙂 I remember paying about £20 for a spring for my Black and generally they all cost similar. Probably better to sell the Mx Lo and buy a proper Mx Pro Lo 🙂 Will probably cost You same as fork with new spring and You will have adjustable rebound as well.