50mm marzochhi open chamber forks

I recently adjusted the compression screws on my forks and now one is leaking. Obviously there’s an o ring on the adjustment screw, but I can’t remember how the screw comes out. I know I have to disassemble the forks, which is kind of a bummer because I just replaced the springs, bushings, fork seals and fluid but of course Murphy’s law kicked in. Any help before I tear them down is greatly appreciated. The pic looks weird, but this is the bottom of my leaking fork.

You will need to remove the bottom valve to replace the o'ring.

The official method is a special long socket that you lower into the lower fork leg whilst undoing the lower nut.

I use a rattle gun while the fork is intact, upside down and applying downward pressure so the main spring holds pressure against the bottom valve. Be gentle with the rattle gun as you can cause the valve assembly to come apart and the shims fall out everywhere (AMHIK).

Thank you. I’m going to be tackling this here very soon since I may only have a few weeks left before the real cold weather sets in and riding season will be over until spring.

I had another look at the service manual and it looks like the bottom valve is a complete unit (without the shims). It might not be possible to replace the o'ring. There might be a grub screw to allow it to come apart. See how you go.

Thank you very much