I recently purchased a used Graco 190ES airless sprayer. First I will say that I do not have much experience repairing airless sprayers. My problem is that when the trigger is released, the gun keeps spraying a little (not a drip but a weak spray). This is an SG3 gun. Will installing a repair kit (needle, seat and gasket) correct this problem or do I need a new gun? Thanks in advance.