Loosen the needle chucking nut.
Pull the needle back slightly.
Add a few drops of the cleaning fluid in the cup.
Point the airbrush gun down at an angle and place your finger over the needle cap. Next, push down and pull back on the trigger to produce a back spray effect. This will free any makeup remnants blocking the nozzle passage.
Clean the cup with a makeup brush or cotton swab.
Push the needle back in and screw and the needle chucking nut tightly. Flush with the cleanser to ensure the passage is clear. Place the handle back on the gun.