Thinner and cleaner will probably be on the to buy list next.
sometimes when I try to clean it out, and fill the cup with water to blast out of the nozzle, it will make some short bursts of water but then thin out to just air, while the rest of the water just sits in the cup. Is that a tell tale sign of clogging?
yikes! I just re-read that last post of yours.
OK, some advice:
drop what you are doing, and go, nae, RUN to the nearest arty store (Joshin will do), and buy some airbrush cleaner. You have paint all over the internal workings of your airbrush, and its getting drier and harder to remove by the second.
Once you have purchased your cleaner, take it home and fill up a jam jar with it. Disassemble your airbrush completely. That means: needle, main body, button, end cap, nozzle.
immerse them all in the cleaning fluid. Leave em overnight. Be careful not to get the cleaner onto O-rings in the joints, as it will rot em. These are sometimes in the main body of the brush, so have a look for em. Mine doesnt seem to have any, so i can dunk it in cleaner fairly happily (but then mine is a single action brush, and therefore simpler.)
This is way more than you would usually have to do, but you've already left your brush for far too long without cleaning it properly. As badruck says, never put your airbrush away without cleaning it properly. That means cleaning it with airbrush cleaner. Its not optional. Water will not do the job. After painting, spray cleaner through your brush. If you do this every time, you wont get jams and wont have to do a major immersion-clean often, if at all.
From here on in, Id strongly advise against using your airbrush without having cleaner available for afterwards. It'll save you a lot of hassle.
Anyway, as we all said earlier in this thread: Airbrushing is neither quick nor easy. It is in fact, rather frustrating.
Are we having fun yet
Edit: I'll summarise the lengthy waffle above for ease-of-reading, and add 1 more thing:
1) Go to the shops NOW and
buy cleaner. It is not an optional extra for airbrushing. You MUST use it EVERY time you paint.
2) Also
buy thinner. Tamiya paint (which is thinner than citadel) should be thinned 50:50 for airbrush use. If you do this with water the paint loses all adhesion and will rub off the model, or worse, disappear when you varnish it (see my Havoc squad of nurgle for an example of this. I had highlighted them v. nicely, but when I varnished em, all highlights disappeared. Horrible.)