Before you give up on the Aztek, try thining the paints a little more. You may find that it's clogging up cos the paint isn't mixed thoroughly.
What type of paints are you using?
Try using both Enamels and Acrylics, you may find that the brush handles Acrylics a little better.
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That is the one thing I like about the Aztek as I hate wasting paint in siphon cups...
I know you can get colour cups for Badger Airbrushes, not sure about Paasche though. I've been using them with the Badger 200 and 150 for about 7 years, they work very nicely. To clean them, all you need to do is use Mineral Thinners and a Cotton Bud

Cougar
Edit: Try increasing the pressure to around 20 PSI, you may find that the pressure isn't sufficient to force all the paint out the brush, so it therefore sits and eventually clogs.