https://www.reddit.com/r/typewriters/comments/1lyef05/slug_work/

James Grooms use a brass wheel brush on his Dremel tool for cleaning his typeslugs.

Cleaning Typewriter Type Slugs by [[Joe Van Cleave]]

JVC recommends 91% isopropyl alcohol (IPA) for cleaning typeslugs.

Brass bristle brushes from Harbor Freight.

Sally's Beauty Supply stiff nylon brush for cleaning typeslugs.

Bergeon Rodico 6033-1 as a cleaning compound (similar to Silly Putty and other older compounds) for typeslugs.