Causes
A fluttering occurs when the nozzle is not tight enough. Inspect the nozzle for looseness or stripping of the nozzle threads before tightening.
A clogged nozzle will produce an undesirable spray pattern. Clean and replace the nozzle and other damaged seals or o-rings.
All tips eventually wear out, with more abrasive materials wearing out tips faster. A tip using Latex may last for 40-50 gallons, while tips with stains will last longer. When you hear hissing as the tip becomes worn and notice the oval spray pattern forming into a circle, it's time to replace the spray tip.
To maximize tip life, spray at the lowest pressure that atomizes paint, slowly increasing until you have a good spray pattern, without tails. If the maximum pressure isn't enough for a good spray pattern, then the tip is too worn.
Different types of sprayers use different pressures. A lower pressure system reduces spatter since the paint is coming out with less force.