I have a suggestion for you Idaho. It sounds like your uptake hose might have a blockage. With the regulator set at about 90 psi, hold the trigger down and press the nozzle of the gun into the palm of your other hand for a few seconds or until you see a little cloud of dust rise up from the hopper area. Be sure to push it right up against your hand to block all air passage -- it won't hurt you, but if you leave space in between you'll just blow holes in your glove. :-)
I also know where you can get
that gun upgrade kit you're talking about too 66Dvert. I've bought a couple of them from TP Tools in Ohio and they're great! It's also one of the best places I've found for other cabinet accessories and consumables.
http://www.tptools.com/Default.aspx