ArmorMaster, by what you described the problem is probably the trigger mechanism seperating from the actuating/roller arm.
Inside your Aztek the trigger connects to this roller ass'y, the top section of which goes further toward the rear of the brush and presses on the lever connected to your air valve, from there the air hose runs to the front of the brush, and exits behind the nozzle at the bottom. (If you remove the nozzle and stare into the brush, you will see the air exit hole)
The bottom section of the roller ass'y is where the nozzle actuating pin is, this controls the rate of paint flow through the nozzle (duh!). And it is at this point where your problem has most likely occured.
There are 2 main reasons as to why the trigger mech fails/separates.
1-BACKFLUSHING: This is a big NO NO with Aztek brushes. While they are OK for the general use we give them, upon cleaning, you should just run thinner through it, and wipe the area behind the nozzle with a Q tip. Backflushing WILL force paint past the 'O' ring sealing the nozzle pin from the body, and gum up your trigger mech. When this happens, the next time you pull back on the trigger it will simply 'POP' off of where it is supposed to be.
2-LAQUERS: The Aztek 'O' ring WILL cack itself if you use laquer based paints, ie Alclad II. When the 'O' ring fails to seal, the same will happen as above.
I hope this helps a bit, please note that the above descriptions for parts, actuating/roller etc, are not what Aztek would call them, but it was the easiest way I could explain them