What pressure are you sweetspotting at (do you have a gauge)? Are you sure that you haven't over-pressurized the valve? That was my mistake a couple of weeks ago. I was starting way too high, assuming my marker needed 200psi+ when I really needed to start at 0psi and work my way up.
It sounds like you know what you're doing and you have the right parts. So, my only advice is to go to your field with a bag of paint and a reliable chorno and take the time it needs to get your rig going.
Everybody: Let's ease up on the red loctite, 'kay? Thanks. MCB Feedback