Pour a small amount of window cleaner into the paint cup on the airbrush. Spray the window cleaner through the airbrush until the cup is empty. Use a cotton swab to scrub any remaining paint away from the walls of the cup. Dump the loose paint out of the cup and repeat the process. This may help unclog your airbrush in some cases.
Unscrew the paint cup from the airbrush. Use a paper towel and paint thinner to wipe it clean. Unscrew the front end and nozzle from the airbrush. Remove the rear piece from the airbrush to expose the needle nut.
Loosen the needle nut at the rear of the airbrush. Pull the needle out of the airbrush through the front, making sure not to drag paint into the back of the airbrush. Place the small parts you removed from the airbrush into a small plastic cup and fill the cup with ethyl acetate. Allow the parts to soak while you clean the rest of the airbrush.
Dip a cotton swab in ethyl acetate and rub the swab along the length of the needle. Wipe the needle dry with a paper towel. Use a fine nail polishing stick to remove small scratches and marks from the needle. Polish the needle to a shine with a non-rubbing polishing compound and a paper towel.
Use a pipette to flush ethyl acetate through the opening where the paint cup fits into the airbrush. Rub the opening clean with a cotton swab. Dip an interdental brush (a brush used to clean between teeth) in ethyl acetate and feed it through the front of the airbrush. Rotate the brush to remove any leftover paint residue.
Reinsert the needle into the airbrush from back to front. Tighten the needle nut to hold it in place. Use the interdental brush to scrub the small parts that were being soaked in the ethyl acetone. Roll a piece of paper towel into a fine point and clean the tip of the airbrush nozzle with it. Reassemble the airbrush and polish it to a shine with a clean cloth.