If isopropol or denatured alchohol isn't doing the trick, acetone works well in making sure everything is cleaned off before applying the trim or patch. Just be very careful you are using it in a well vented area, with no open flames or sparks, it is highly combustible and the fumes aren't good for you. Monocote and other coverings are very tough chemically speaking, since they are made to stand up to glow fuel. But with glow fuel, you can have allot of oily residue left, even after you think you got it clean, several cleaning applications of solvent soaked paper towels may be needed to ensure all the oil or other contaminants are removed.

Good luck with your trim project.