My best guess is it's oil both from oiling and from hands. I was told this machine was the sellers mothers main machine for many years. This color is the worst on the bed but it is in other areas that seem to be consistant with oil and grunge on any machines I clean.
Sewing machine oil did nothing. Tuff Stuff makes the cotton ball come back brown so I think that is dirt but the color isn't changing. A bit of TR-3 seems to make the cotton ball come back dark grey and that doesn't feel right, so I called a halt until I could get a better plan.
It powers up and all the switches move but I am not sure how they all work yet and the motor isn't strong as in it needs interiors cleaned first before playing too much with it. I bought this machine without a power cord but from someone I have bought other machines from so i took a chance. I have cords for it now so it's time to clean it up and see what we have here.