Need help quick, Paint gun problem

[bowtieride]

so i went to start painting my truck a few hours ago, and i was spaying an old hood to get my pattern and spray adjusted right. I had it just about right when the paint started leaking out of the tip, and now it wont stop inless i tighten down the adjustment skrew all the way. I cleaned it all up and its still doing it. I can get the pattern right, but when i stop spraying it just leaks paint everywhere. Ive checked the air pressure and its not that. I dont know what to do now, and i have a gallon of primer already mixed with the reducer.
Thanks for any help guys!