I just saw that you said you may use copper spray. Save yourself some headach and don't. It will be way to thin to seal anything. And before you apply the grey RTV Make sure the surfaces are clean!! Use a scotch brite pad and scuff all surfaces. Then wipe it down with like brake clean or something that evaporates on it's own. Then apply the rtv ect. Sometimes the ic's arent perfectly straight so that may be why your having some issues if it's always happening in the same spot. You could even use some sand paper to scuff things up. buyt agian make sure the sufrace is free of oil and dust ect. Also let the rtv get a little tacky before you put it anything on. And let it dry all the way before you start it.
