Bubles problem



My airbrush is not working well. I can't do anything if I'm not pulling trigger full back.
The paint is coming over the cup with air boobles.
looks like you need to clean it 100%, the nozzle may be clogged or you could have a cracked nozzle.
but it could be a bad seal where the air cap screws on. lot of things can cause this but you will have to inspect everything to figure out what the problem is.
Disassemble the the front of the airbrush and clean everything well, especially the nozzle. Use a magnifying glass or jeweler's loupe and hold the nozzle up to the light to inspect the inside. You'll be amazed what collects in there. When you put it back together make sure you use some chap stick or bee's wax on the threads to seal the nozzle cap (regulator). If you don't seal the threads, air will flow into the area of least resistance, which is the cup and you will get bubbling. Btw, acetone or lacquer thinner really cleans the nozzle great. Don't soak the entire airbrush in these solvents, just the nozzle. You may also need to use a plastic dental pick to clean inside the nozzle. Do not use anything metal to clean inside the nozzle as its brass and you'll damage it. I now avoid most of these issues now because I started using SEM's Waterborne gun cleaner. This stuff works great on water based paints.
I had the same bubble problem with my g77 that I bought used, a lot of dried paint in and on the gun

Cleaned it numerous times, still had the problem so I started searching online and read that if the nozzle isn't far enough forward it can cause bubbling.

I had cleaned the brush with acetone to get the dried paint out and I thought the tiny O ring at the nozzle might have swelled so I removed it and voila' the bubbles in the cup ceased and it sprays like a champ.

Good luck with it, Jim