I use Glenn's cleaning solution for the painted parts.
(CANNOT thank Glenn enough for this. It has replaced ALL of my other cleaning solutions for sewing machines)
I use Brasso, brass brush, and/or 0000 Steel wool for the metal parts.
This machine took about 2-3 hours to do the cleaning you see here. (I am too lazy to use any methods which take longer...hehe) I have not finished cleaning the underside, but I will tomorrow night.