hmm, I recently made mention on another forum page of something that I hoped would be helpful to others. I've used airbrushes for many years now (not necessaries very WELL!) and when I started I was, by definition, a beginner. after a while I found that I couldn't paint unless I turned the regulator pressure up very high and, crucially, I was getting air bubbles blowing back into the paint cup. no amount of cleaning and looking for blockages helped. I was at my wits end until some very helpful Americans and one Scotsman on an airbrush forum (thank the lord for forums) suggested that I had possibly, through ignorance, allowed the trigger to snap shut under it's spring pressure. being an engineer I knew the protocols of assembling the needle carefully so it was normally closed just up to but not forced into the paint nozzle BUT being careless and/or inexperienced allowing the trigger to self close could have allowed it to force into the nozzle, damaging it invisibly but irreparably. a slightly too-rich paint mix, even with clearance between the tip of the needle and the nozzle could have hydraulically damaged the nozzle. I eventually bit the bullet, bought a nozzle and hey-presto! expensive airbrush fixed
my advice, if it helps anyone is to treat your airbrush as a precision instrument ( I'm sure we all try but accidents/mistakes happen in case anyone gets up on any high horses, we were none of us born as experts) and if there are bubbles and no blockage suspect that tiny but oh-so expensive little piece at the very front. happy airbrushing, and thanks to Brett Green and his colleague who give those brilliant displays and airbrush talks at Telford each year.