Dude
it sounds like theres to much pressure going into your shocker unscrew your maxi flow reg cap right the way out (dont unscrew all the way off), so that theres no pressure on the gun.
Does it still leak??
if not then slowly increase the reg pressure until the guage reads about 180 psi, which should be enough to fire the shocker.
If it starts to leak as you increase the pressure then it sounds like a seal gone in the maxi-flow, in which case you will need to strip it and replace the seals (about £15 from smart parts for a full overhaul kit) other than that you could try stripping the maxi-flow and re-greasing it. Let me know your email address and ill send you a tep by step how to strip and do your maxi flow
cheers
Bruce