Tip: of the 3 things WD-40 is actually useful for on a typewriter, one is cleaning and giving a nice sheen to crinkle paint safely. Apply lightly on a clean rag. The other two are cleaning white-out off plastic card guide without fogging the plastic, and removing the calcified masking tape often found on SCM portables.
via Ted Munk as a comment on a YouTube video
Fossilized Masking Tape Removed Cleaned from Typewriter Body by [[Phoenix Typewriter]]
The paint on the metal of the SMC 6 series typewriters will generally stand up well to lacquer thinner and along with scratching can be used to remove the old residual masking tape often found on these typewriters.
WD-40, gun bore cleaner, and Simple Green generally don't do much to this sort of tape residue.