hHow clean is clean? I have scraped it with a a scraper, wire brushed the residue left sticking to the joint. There is still a thin layer of sticky black residue left from the wire brushing on parts....
I used Mineral Spirits just as Eternabond and Dicor suggest. No harm what so ever to the rubber membrane if you just apply it to a cloth and rub. Does a great job and takes off residue fast. I've never seen any hint of the rubber having issues with it.