[aixguy]

sounds like the connection to the plastic dip tube is loose or the tube is cracked near the top where it goes into the cap. Or maybe metal tube from the cap that goes into the brush has a crack.
If you take the bottle off the brush and put your finger over the hole where the bottle plugs in, then air on and pull tirgger all the way back, you should feel suction on your finger. If you do feel it and it is fairly strong, your problem is in the cap or bottle or tube. If no suction then the problem is in the fornt end of the airbrush, either nozzle or cap..
I am guessing plastic tube..