First of all what nI would do is pull the set screw out along with the roll locks that the screw tightens into, and clean it and inspect it for cracks, or being stripped, then the base of the carb should have 2 o-rings small and thin, and if it doesn't you need to pick up some and your hardware store, slip them on with a little vaseline put your set screw and lock rollers that the screw tightned into, and you should be good if your lock-rolls and set screw is shot then order a new one part #G70369-05 and if you have problems threw Cen go to Nitro RC Hobby, and they'll have it, just click on Cen Parts and keep scrollin until you find the kit.