the last pile of melted gunk I had, came off with bug and tar remover. I didn't use that all the way down to the metal, but putting cotton balls saturated on top loosened a lot. I had nothing to lose on that machine. I did coat the metalwork I wanted to protect with oil before positioning the cotton ball, and didn't lose any paint.
What I used on the Pfaff 130 in the pictures was Rubbing Alcohol 91%. The before picture shows a lot of black gunk, a small pile, and it came off with Rubbing Alcohol on paper towels. Wipe it off quick though. :)
I bought a Singer 15-30 treadle with gingerbread/ tiffany decals years ago that had an added on motor with 'melted' wiring. The melting was so bad that it had run over the up-right arm, over the bed and down onto the wooden belly pan. Funny how older wiring either melts into a goo or becomes totally brittle.
I removed it with kerosene. I soaked small flannel rags in kerosene. I then placed the rags on a small section of the wiring puddle for 10 minutes or so then rubbed the puddle with this rag. I continued to repeat this using a fresh rag each time. This action slowly removed the puddle a tiny layer at a time. Nothing quick about job. A small amount of the goo never came off of the belly pan.
This machine is now drop dead gorgeous. I had no damage at all to the decals, but the shellac on this machine was intact. If the shellac had been compromised I suspect that I would have seen decal damage.
I have some work to do on a couple melted up machines. I'm going to try all of the above and see what gets the goo off. Just not today.
Well if all else fails you could soak it in kerosene and light it. That should "melt" the gunk off. LOL.