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....
3M adhesive remover. Available at any NAPA store, not cheap but will save you hours. Pour a little on an area, wait five minutes, wipe in ONE direction with a clean cloth. Do a second or third wipe with a clean saturated cloth. Do not rub back and forth, that only makes a smeary mess. No need to rinse.