N_Cook wrote:
0.5mm thick PTFE , but any soft plastic would do probably.
With a fine needle make, as closely spaced as you can, random holes at
the straight edge of the plastic, so the reverse looks like a cheese
grater. Immerse the grater-end in some meths or similar and insert a few
times into the socket. And also clean the end of the ribbon of course.

Why not just use a piece of paper or cardstock dipped in your solvent of
choice, insert and remove a couple times?