Straightening a Bent Needle
Maybe you got a little bit too close to your work. Or, maybe you dropped your airbrush or stubbed the needle during installation. Somehow, the needle got a little bent. What do you do? Here are some methods I've come across.
First off, how badly is it bent? Take a look at the sketch above. Notice the needle is bent so much that it won't pass through the nozzle. Whatever you do, don't force it. Nozzles generally cost more than needles and they are very fragile. Use pliers if you have to, but straighten the needle enough somehow so it will pass freely through the nozzle. If you can't straighten it that much, you might as well clip it off with a sturdy wire cutters and buy a new needle.The bend might be so tiny that you can't see it with the naked eye. The only thing you may notice might be a bad spray pattern. But, if you run your fingernail lightly along the tip you may be able to feel it. I've found that I can often straighten this type by just dragging the needle across my foam cutting mat while rotating it. Try to keep the taper of the tip flat against the mat. A little pressure on top with your finger might help.
If the bend is a little more serious, I've done the same thing only with a fine whet stone or very fine polishing paper on a flat surface. Be sure to rotate the needle so it stays round.
The coin trick
A very common suggestion is to pinch the needle between two coins and pull it out. I haven't tried it, but I see it so much that it must be somewhat successful. You would probably have to repeat several times. You could also use one coin and a flat surface like a piece of glass. I found this video that claims a wooden hex shaped pencil works well. Again, I would rotate as you pull.
Last ditch effort
If straightening just doesn't work, you can always try to reshape the needle as I did on my Tuning page. A straightened needle may never be quite as good as a new one. But, maybe you can get it good enough for most purposes.
If you know of a method I haven't mentioned, please pass it along and I will include it.