'06 EC 300 Marzocchi fork leg leaking all over floor
 

Hope this pic is visible;

I'm laying on my back looking up at the right fork leg. You can see the drip forming, it's lost a LOT of fluid all over the floor. This happened spontaneously this last week, can I assume that the insane cold weather we had recently just caused the internal o-ring seals to shrink and now fail? Since there's oil surrounding the larger hex nut, I'll assume the leak is coming from a larger o-ring sealing the nut.

I don't have a manual for the Marzocchi fork, but I assume the small screw is the compression damping adjuster, and the large hex nut attaches to the underside of the damping cartridge?

I know I'll have to pull the top cap off to re-fill with fluid, but can I remove that large nut (and the adjuster screw with it) under spring load to replace an o-ring seal?

Sure, thats actually the easiest way using a pneumatic impact tool and the spring tension to hold it. Tip: A six point spark plug socket with the lead in taper ground flat fits VERY snug on the soft alloy base valve hex and will minimize the chance of damage.

You should really remove the fork to properly fill, bleed, and set the oil level.

Can you clarify this "...lead in taper ground flat..." tip?

After I entered this post I found the Shiver 45 manual on this site. Page 50 describes removing the bottom valve (the troubleshooting section describes my problem exactly, says to replace the bottom valve o-ring) AFTER the top cap and spring/oil have been removed. It specifies a couple of specialized tools.

Are these tools necessary because they assume the spring has been removed? Will the spark-plug socket method work with the spring still installed? Will this method work WITHOUT the spring installed?

Yeah, I have to pull the front wheel anyway to swap tires, so I'll pull the fork leg and drain/fill properly. I just want to be sure I can get this bottom valve off before I pull the leg and THEN discover I need special tools to do it.

Lead in taper is the taper cut on the inside edge of a socket opening to allow easy fitment over a fastener. It does however reduce surface contact area, not what you want for a soft aluminum base valve hex. Grind it flat until removed. An old LTR tip.

I only mention the spark plug socket because it is a particulary tight fit, which is good, and has a thin wall that will fit.

No special tools needed for this fork with the exception of a 45mm seal/bushing driver, nice thing about it.

Got it now, thanks!

And those Shiver 45 parts would best be ordered from where?

I'd start with the guys that sponser and contribute here.

Tried, but the damper turns....
 

I finally took a spark plug socket and ground down the lead-in taper, and with the fork cap still installed (and the wheel axle in the axle clamps to prevent rotation), and I can get that large external valve nut to turn, but it feels like the damper internally is turning.

Is this possible? I thought the valve was threaded into the axle clamp itself, but looking at the manual, this doesn't look to be the case.

You mentioned using an impact wrench. If I can turn it by hand, would an impact wrench somehow over-ride the damper rotation and back the valve out?

Thats right brider. The whole internals will freely turn within. If you remove the fork from the triple clamps, turn it upside down and have a friend compress it, the spring tension can be enough to help get it undone. An impact also works as with each impact it allows it to crack and undo a little more. Same way a rattle gun can undo a sprocket nut with a bike in neutral. In the past I used a battery operated impact with a good socket, and the fork upside down compressed. Came undone nice and easy.