-First take off the cap
-Now get a small tool (i used an allan key) to push out the pin.
-the "plunger" and a spring should fall out and should look like this:
some more pics:
Now lube up those orings like theres no tommorrow to hopefully create a seal:
that list pic is pretty bad but w/e
now after you lubed it up put the spring back on and put the smaller side in first (pin) and push it down with the allan key and screw the cap back in.