make sure the rotor center "tang" has a bit of tension so it compresses a bit when you install the cap down on it. If there is a gap the arcing will burn the surroundings in no time. also you might put a slight bit of dielectric grease on the top of center tip of the brass rotor tang where it contacts the underside of the cap, the area in question. Helps with radio static also. EDIT Morty beat me to it