Nice setup you've got there, FHF! Remember that to get a halfway accurate measurement on that 24oz you need to pick it up and swirl it around to get the agitator to stir up the liquid so yo can see it on the read panel.
TVadna, got to replace that o-ring or it will continue to leak (Call me Captain Obvious!). I'd bet that the reason it seems like the tank valve is not cutting off the CO2 is that the needle valve lets such a small amount of gas through that it takes a minuite or two for it to bleed out. You might want to consider one of the little Atomic (i think) PB reg setups. I'll post a photo of my rig when I get home today so you can see it.
Nikon Pimp #084
"The legal quarter of tight lipped men, push for order, then repeat again." KTP