Hey guys are there any videos of an RT pro disassembled or an exploded view on re assembly? After unscrewing the back portion (velocity regulator I believe it’s called) is there supposed to an o-ring in the hole there? (I don’t have one here)

On the front where the regulator valve assembly there is a circular brass piece with 4 notch cut outs, is there supposed to be an o-ring seated into the middle of that brass piece? (I have an o ring here) and which way should that brass piece be facing? (4notches be facing the velocity reg.)

I watched the old classic RT disassembly video and looks like the small brass piece is flip around than how I have it in my gun. But I also have a exploded view of an x-valve which seems to be more accurate to what I have which shows it’s in correct.

I’m just getting back into all this and my gun been sitting for a while. Appreciate your guys help