Looking for some info on working with a detail HVLP gun. Mostly want to know if the problems I'm having are fixable, or if it's just because "harbor freight quality". Attached is an image of the detail HVLP I use. Highlighted at the top in red is an area that I'm seeing a problem with leaking. There appears to be a seal inside the cap, but not sure if maybe it needs to be replaced? It's a bit of an O ring, but honestly looks like it's made of a substance other than the usual rubber. It's more of a paper pulp color. Highlighted at the bottom area in red is the adjustment that allows me to quickly change the amount of air going into the gun. It works fine, but, as the image indicates, it's pretty loose. Loose to the point that when using the gun and wearing gloves, I sometimes see a change in the pressure as the fabric on my pinky finger brushes up against it while moving. Is there anyway to make it a bit more stiff in it's motion? Thanks.