Urgent Help! RTI leaks at this pin opposite of the regulator.

Yupp, tried adjusting the reg. Both ways. Nope.

Tried to wiggle the pin, even found an adjustable wrench in my field kit to try to turn it slightly. Nope. It changes the amount of hissing air escaping, but no stopping....

Scanned all webpages, Youtube, parts diagrams, but nope — no-one explains what that pin does....

I've got all night at my cow range, so, if you've got more suggestions — I appreciate them! 👍🏼

Matthias 😊
It’s the regulator shaft so keeps it all in line there’s a small o ring inside there could have moved.