I picked up a second 15-91 the other day and didn't realize just how grimy she was until I started cleaning her. In the first pic I cleaned a small area to see if I could find any pretty black shiny paint underneath and I did. But it was very hard just to clean that small area. I almost put her back into the table and said ....later.
It was going to take me weeks if I tried to do it the regular way with soft rags and oil. I am not sure what the grime is but I certainly do not want to leave it on her and I certainly do not want to touch it while sewing. My guess is tobacco grime with dirt and grease mixed in.
I am not necessarily lazy but as a true Pisces I always search out the paths of least resistance while accomplishing the same goals. LOL So I searched out today my path of least resistance and thought I would share. You can tell in one of the photos the whole machine looks like she has a very light weight crinkle paint job. The whole machine felt rough and textured all over. YUCK!!! Since I do not know what the grime is I am using a respirator, safety glasses with Turtle Wax bug and tar remover and my secret weapon....Sonic Scrubber by Windex. Link below:
There are other bands of Sonic Scrubbers too.
I lightly spread on two drops of bug and tar remover onto small area and then use a small brush head in the Sonic Scrubber kit and go lightly over the area with the bug and tar remover. Off comes the grime. It actually is taking two times because the first time you can feel the brush starting to slow down and it feels like it is just swirling around the gummy grime but it has loosened it up. So I wipe the brush clean and also the area on the machine and do it again and Voila' super shiny clean black sewing machine.
I also use the sonic scrubber set for wood work, grout, and well just about everything. It has made cleaning fun, well....more fun and so much quicker and my hands, fingers and arms do not get tired. Do not use on decals...