I always take my guns completely apart after painting. Take off the cup. Throw the air cap and fluid tip in a cup of laquer thinner. Remove the needle and wipe it clean with thinner and a rag and relube it. Clean the gun passages with brushes, tooth picks, Q-tips, etc, until no paint residue remains. Do the same with the cap and tip. Reassemble and shoot a little clean thinner through it. Maybe a little overkill, but I'm just a hobby painter and I've got too much money tied up in my guns. Plus I've never had a problem so far, knock on wood. Also keep an eye on the fluid tip gasket inside the gun and make sure it's in good shape.
Bob
