Pulled the seat and tank today to start cleaning everything up. I noticed on the back of the cab behind the tank it has a bunch of gas smelling thick tar/dirt build up. I started scraping it but was really making no progress. What's the best way to remove all the gunk? Some of it is soft like tar. I was thinking of soaking it down with a good degreaser or something to break it up. It's pretty much the whole back cab behind the tank. Ideas?