basepaint
Air-Valve Autobot!
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He said no bubbles unless he blocks the tip and back flush's it? I agree with you squishy blocked nozzle or bad nozzleI'm not familiar with these brushes, but I remember reading somewhere that to get vacuum, the end of the nozzle has to protrude slightly. Not sure if this applies to this particular brush??? Thought I'd mention it though.
The only other possibility I can think of is a badly blocked nozzle. I know its new, but they sometimes get tested in the factory. Was there a piece of paper with a test spray in the packaging? Even though the needle is passing through I can still be blocked. Does it feel spongy or sticky if you gently move the needle in and out by hand with the chuck undone? That's one sign of a blockage.
Are there bubbles in the cup when you try and spray?