I've got exactly the same issue. As a note and in my defense, I've worked with o-rings and mechanical things for more than a few decades.
1. Carefully backed out the #2 reg to flush plus a wee bit, checked the pressure 137 bar.
2. This is where I got creative...removed the bottle completely, dry fired the gun a few times until the air bleed out entirely,
3. Screwed in the #1 reg until very slight resistance and back it off 1/2 turn.
4. Started backing off the #1 reg. checking the pressure and....next to butt-kiss.
5. Kept backing it out until air started leaking out the #1, yep, not a good thing.
6. Repeat #2
7. Screwed in the #1, reattached the bottle, and 11.3 bar all the way until the reg started leaking.
8. Removed the bottle and bled the system.
9. Removed the WTH
10. Removed the reg.
11. Removed the adjusting screw
12. Mild cursing as the top o-ring was absolutely shredded. WTF I'm 99.873% certain it wasn't me.
Looks like a call to FX on Monday, because I've zero idea how to tear that reg apart or what size the o-ring is...and I'm moderately certain that ACE hardware doesn't have one.
Now the FYI, I was running about 106 Bar on the rear but the SD was pretty bad, so I wanted to do a bit of a tune. Note to self....don't F with something that works....I NEVER LEARN.
Edit....Ok this is weird, there are only TWO o-rings on the adjustment screw according to the FX schematic, so...why in the H is there the shredded one when the other two are looking pristine?
And where in the H are the Belleville washers? I don't see a darn thing and the schematics don't show a darn thing.
Edit, ahhhhh found the little suckers, thanks to a video, they are at the bottom of the hole on a pin, you get them out with a tool the guy sells or a hemostat works great.
Edit. found the bad o-ring, on the top of the adjustment screw, it's a 2x1 90 just lightly shaved off, gut feeling it was bad and when I made the adjustment it let go. Ordered a kit From Amazon, Capt. O-ring, faster than mucking with the dealer.
