Hi all! I just bought a graco 395 st pro off a guy for fairly cheap. I know pretty much nothing about the sprayer and can't really tell if it even functions properly. I hooked a hose and gun up to it today and tried to run it with water (not paint) on prime and no water would come out of the prime hose. But when i sprayed the gun the water sprayed out normally it seemed. Motor kicked on and pumped.. So basically I'm wondering why i cant get any water to come out of the prime tube? But the sprayer seems to spray properly when i pull the trigger on the gun? Could the prime valve be stuck on spray internally ? Any input would be greatly appreciated!!