Need help with Xvalve - will not fire, still holding pressure. How do I depressurize?

[GlassPancakes]

(I tried posting this thread before and I couldn't seem to find it - so if this is a double post, please feel free to remove.)

So I attempted to tune my new Lvl10 Xvalve with UL-T this weekend and it didn't go well. I started last week by removing all but 3 of the shims in the UL-T on/off (there were 5 present before I removed 2) and I didn't mess with the Lvl10 at all yet - so the carrier/shim set-up in the Powertube was the same as when I received it. I took it out to the field, gassed it up, and while the sear rod is making full contact with the trigger and the trigger will depress, the valve will not cycle. I would have disassembled to put more shims back in... but since the marker won't cycle, I can't depressurize to work on the valve. I tried running the velocity adjuster in the back all the way in in the hopes it would degas out the back, but nothing. Then I tried running it out all the way, so that it was just hanging on by a thread or two, and nothing there as well. I can't disconnect the quick connect because the valve is still under the full 800psi required to operate the valve. I was trying to fix the half-stroking (is that the right term?) that was happening to my marker under rapid fire - it will sputter and seems like it's not fully cycling if I try to fire quickly.

I've had an Automag for 20 something years now and used a Lvl7 Classic valve for all but the last month or so. I've never run into this problem before and I am freaked the hell out by the idea of trying to disassemble under full pressure. How do I degas the marker so I can work on it safely? Can I take it apart under pressure or will I shoot parts across my apartment in doing so?

Any help is deeply appreciated.

[luke]

I took it out to the field, gassed it up, and while the sear rod is making full contact with the trigger and the trigger will depress, the valve will not cycle.

You need a gap between the trigger rod and the back of the trigger after the marker is aired up, gap should be about the thickness of a credit card.

[GlassPancakes]

So there's a good chance that my sear rod is too long? Any idea how to get that fixed while the valve is still under pressure?

[luke]

So there's a good chance that my sear rod is too long?

Yes

Any idea how to get that fixed while the valve is still under pressure?

Have you degassed the marker and removed the tank?

[GlassPancakes]

Can't degas the marker because it won't cycle and I'm using a Flatline Reg that runs straight into the valve. The on/off on the Flatline is off but because the marker won't cycle, I can't get the air back out of it.

[luke]

I've never had a system locked up like that and I've never used the Flatline so I dont understand how they work.
Maybe if you push on the bolt tip with a wood dowel or something and maybe get it to vent some pressure(?) Could you maybe loosen an airline fitting(?) Be careful you dont lose and eye or send a fitting flying across the room, truth is I'm a little worried even suggesting that..