My first question would be how high you are running your machine. cause i have never experienced that but then again i don't run my machine high like a jack hammer.. That knob is only good for one thing... Give or no Give... that is all but if your machine is spitting like that u probably are running ur machine high, And using hard nipples.. Use soft ones don't bend ur needle bars not ness.. Bend your needles down instead from the solder joint just slightly this should solve ur problem