When I usta repair Xerox machines, I used trichloroethane to get rid of it.
Do NOT put trichlor on hot metal (such as a fuser), or else you'll end up
with phosgene gas, which is -- shall we say -- slightlu harmful. (It was
one of the war gasses used during WWI).
I've heard that trichlor was outlawed, but I still see it around. My
favorite all-around solvent is MEK, but I haven't tried it on toner.
manney(a)nwohio.com