The damaged areas were first sanded with a file, degreased with TECHNOSOL and then sealed with DUOTMEL.
Sanding with sandpaper (grit 80-150) and another coat of DUOTMEL (only on a few visually imperfect points).
Again sanding with sandpaper to clean (400 grit) and repainting with HOS spray.
Finally, of course, a total wash with NOVALON 1:5 and the set is as good as new again.