The gunk on my inherited 403 was from those unbelievably nasty little black cigars my mother smoked as well as the pipe my grandfather smoked. Patience, paper towels, cotton tipped sticks, rags, gloves, and my home-brewed cleaner/unsmeller of choice did the trick. The poor machine had literally dripped nicotine from the piece joins and the areas that were originally painted a pinky-tan was brown. It's back to the pinky-tan and nothing oozing out of those joins. It works gangbusters too.
Pat