Fork disassembly

Hey fellas,
I have a 1981 GPZ 550 rat bike with KZ 550 LTD front forks. I need to change the seals as one is leaking. My question is, how do i get the top of the fork undone.? There is the air valve with an 8mm nut at the bottom of the valve on the top of the fork. I can turn that and I heard the air escape as I did that first turn. But it just spins in there. It dosn't seem to come out any further or go in any further if I change direction. Do I just tug on it and pull it out? I didn't want to break anything, so I thought i would ask the experts for help. Any advice would be greatly appreciated.

My guess is the the fork plug is spinning when you try to remove the air valve.
The fork plugs are held in place by circlips (using the diagrams at partzilla for the 81 D1 - the plugs are listed as Spring Seats.).

Relieve the air pressure first. You have to depress the plugs to remove the circlips.
Keep in mind that the plugs will be under spring pressure.

That's it Martin! Thanks....rookie move on my part.