First Time Airbrush User

Been practicing with Paasche HS airbrush with only the paint cup.

My question is that I had quit a few pieces to prime including the body so I decided to use one of the bottles that came with the airbrush so i would not have to stop between pieces to refill paint cup. The problem is that the airbrush would not pick up the paint in the jar and the jar was  half full. Primer was 2 parts primer and one part thinner which worked fine using the paint cup but not in the paint jar. Do i need more air pressure or  do I need to fill the  paint jar to 3/4 full or more thinner? Was using Model Master primer and lacquer thinner with No# 5 needle. Compressor i got with the airbrush is oil less and is a tankless compressor.

                                                                           Thank You

Source: http://cs.scaleautomag.com/SCACS/forums/thread/936903.aspx

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