I've never heard of someone using abrasive materials to clean any parts of an airbrush, that is a new one, and can't imagine it's safe to use on a needle. Needles are sensitive little pieces of your airbrush, the tiniest defect will have your paint doing all sorts of things you don't want it to do. I use a method similar to RayburnGuy, paper towel soaked in airbrush cleaner and run it down my needle a few times between certain color changes and at the end of my painting sessions. Finish off with a paper towel soaked in water to get the excess airbrush cleaner off and viola. Clean as a whistle. As far as the caps, a q-tip soaked in air brush cleaner and run around the inside of the caps a few times is sufficient in cleaning those little guys out, same with the fluid bed.