A few years ago I bought 2 new spray guns.One is a touch up gun. I have used them both twice. I cleaned them good each time I used them. It has been over a year now and last night I tried to use the touch up gun and It spits and does not spray right.I tried to put some thinner through it but no difference. I took it apart and it looks clean.I also noticed it is bubbling air in the cup on top. It is a HVLP gun. Is something plugged or something?

 

bubbling in the cup is caused by a bad air cap on the fluid cup...
make sure it is not blocked and remove cap and hold the trigger in
and watch the cup, replace the cap and open the vent, should clear
it up.....go to www.autobodystore.com and they have great forums to ask and get the advice you seek........