I'm glad the procedure worked for you. If you coat the burnished surfaces with something that prevents oxidation, that will extend the running time between cleanups. Light oil, No-OxID, Conducta-lube, etc, etc. Anything that coats the metal, creating an oxygen barrier. But no heavy grease - that will probably degrade the electrical connection.
I take the burnishing one step further: I actually polish them to mirror finish, although I have not done that to these particular models.
See
https://www.therailwire.net/forum/index.php?topic=32605.0 (specifically the initial post for a photo of the polished white metal frame, and then the Reply #16 for more info on what I use to polish the metal).
