(quoted from post at 11:00:42 12/16/22) You're not going to like this news, but that is a guide peg for the internal piston. The peg itself comes
out from the inside, and is one of the last parts to come out of that housing. Meaning pretty much a
complete disassembly of the box to replace the o-ring on that peg.
With reference to the image below, the guide peg is #41, and the leaking seal is #42. The image makes it
look like the peg comes out from the outside, but it does not. It's wider on the inside of the box.
I've seen people put silicone on the outside of the peg to try to seal it, but that is an effort in futility
because the housing and the peg are under full system pressure. I doubt even JB Weld would stop it, as much
as I'm a believer in the stuff.
Steering box breakdown