This can occur when the airbrush is dropped, mishandled, or sometimes lent to a friend. Let's look at the parts of the airbrush and how they apply to its proper performance. All internal mix airbrushes have needles that run through the body to control the flow of paint. These are honed to an extremely sharp elongated tip that, if bent, will result in an undesirable spray pattern. The harder the material of which the needle is made, the harder it is to bend the tip.
Damage can occur to the needle during the cleaning process when it is removed from the airbrush.
This may be remedied by rolling it between two flat metal objects, gently twisting the needle to straighten it. Be aware that if straightened too many times, the result will be tip breakage and replacement will be necessary. If dented, it must be replaced, and the parts are readily available at art supply stores. When the head assembly is replaced, it must be seated properly and tightly. However, be careful not to over-tighten a head assembly or the threads might break off inside the body of the airbrush.