
Thanks for the suggestion but in my case there is nothing to nail to. A shingle must be attached to thick (~2mm) rubber that’s just formed to be vertical. Perhaps I need to rivet the two rubber pieces together. Or I might try construction glue again but also get a couple metal plates and screws to clamp them together as a permanent clamp.
I don’t have anything specialized like simple green, but wouldn’t acetone or denatured alcohol make a decent primer? I think priming the smooth rubber surface should be the easy part but it’s the bitumen band that’s tricky. It has a sandy texture and sand crumbles off when I rub it. Perhaps I should steel brush it where it needs adhesive.