Because you aren't totally new to an airbrush I'll assume that you are right and your brush is a clean as it should be. (if in doubt soak the head unit in restorer - minus the seal, use a long bristle hairy brush to get into the nozzle) Has the brush been sitting idle for a while ? if so the a good soak/scrub/rinse repeat should have been done. its amazing what we leave behind unintentionally
try upping the pressure a little, if your paint might be to thick to start a good flow, my cm-c is happier at 25-30 at the reduction you stated. If you aren't getting the fine control that you want/need then add some more reducer bit by bit. sometimes just a drop of water in your paint cup and mix will give better flow. my paint are now a few years old and even though I give them a really good stir (to get to all the thick stuff at the bottom) they are starting to thicken, I find water is easiest to loosen the mix, Createx claim there is a pot life if you add reducer to the paint so water seems safer as long as you don't go to extreme.