I have a small leak at the edge of my roof, right before it hits the flashing. I think the roof is a torch-down (slight pitch). There seem to be gaps in the black goop that seals the uphill side of the flashing ("black goop" = technical term; hope I haven't lost anyone : ). Could I use Blind Nailing Cement to cover that area to re-seal it? If not, what is the right stuff to use?