Hey Miriam, why do you suppose so many of the 400 and 500 series machines end up that way? I'm wondering if it has anything to do with that fiber gear. It makes the machine seem louder than it needs to be, maybe people try "anything" to quiet it down? The 403 and the 503 weren't nearly this grungy. I really thought it was permanent. It didn't come off if you scratched it with a nail or anything.
That machine now that it's cleaned up and properly lubed, seems really good. It still flings black with the new grease, but I think that will happen until I clean the fiber gear of every speck of dirt and then some. I haven't had any time to sew on it, but when I got it, it ran slowly and made the growlies that most people complain about. It's quieter now, while test sewing, and after full disassembly, I had the piggy nose off and everything, it ran really nicely during the test stitch phase.