Main reason I got rid of my ceramic tubes.
So, if the plastic is melted good, run the car and heat them up to the point you can move the crud. Paint stick, tongue depressor and/or anything that you can scrap with that does not scratch the coating.
Then, you need to get it down to those nasty black lines that seem to fill the areas you can not scrape.
Let pipes cool and try a small screw driver or pick. Sometime I could get a chunk to pop off.
Once you are fed up with that - 3M medium grit and polish out the residue.
This is just what I had to go through.
Hope this helps.
