The first thing I do each session is to spray straight water through the gun to make sure there isn't a problem with the gun. If it won't spray water it won't spray paint. If it will spray water then it should spray paint if the paint isn't to thick. Sometimes the neck part of the cup needs cleaning. I use the paint bottles that attach under the gun and the paint is bad to dry in the filler tube. First thing I would do is get air coming through the gun with out any paint. I would start taking it apart from the back end of the gun and see where the air stops passing. Airbrushes are simple, just small parts to work with. Curing no air is harder than curing a small amount of air. Because you may not be able to get cleaner deep enough to penetrate the dried paint or trash that gets sucked into a brush. If it is a piece of lint, like off a pipe cleaner, solvent won't remove that. If you are considering buying a new brush, it sure won't hurt to tear that one all the way down first. Good luck. Musky Glenn