Thanks Julian and loCo
As suggested I did remove the nut and pump up the -chamber after the + one.
As previously said its a bit if a faf but it works.
The foot nut is in fact 21mm so replacing it will make no difference, but what I did not find is any rubber seal between the foot nut and the outside base of the fork, I’m thinking either it seals inside or it’s missing. Only because the foot nut has a small recess were it contacts the fork.
The next big question is why is the thread so short? Was the fork rebuilt incorrectly when someone serviced it or were early connections just that short.
I know I can get the pump to work by cutting the height of the 10 mm nut in half, it will gain mr the 4 mm I need to connect. . What do you think ? Too cowboy?
The fork seems smooth and works well and holds pressure, so next time it’s due for a service I can check out the assembly inside.
Don’t want to go to the trouble of posting bits just yet as I’m in Cyprus, but it’s good to know that when my curiosity gets the better of me and I strip them you might be able to supply the bits.