[Swimmer]

The housing on this air brush that fits onto the front of the gun and covers the nozzle through which paint flows, comes apart, and is actually a two piece unit. When I cleaned the nozzle I always took the housing off in one piece. Low and behold red paint found its way into the threads that screw both pieces together. A minute amount, a very minute amount was located there. This was enough of an obstruction that caused the front and back of the two piece nozzle housing to not seal properly and allowed air to backflow into the air gun and bubble up in the bowl. Clean the affected area and voila, it works just fine again.