Cleaning Copper Contacts?

[Chuck Guzis]

Looking very carefully at the photos of these contacts, I believe they're simple tinplate.  This would fit with the inexpensive phenolic PC board material being used.

Kepro makes a non-electrolytic tinplate solution that comes as a dry powder and is mixed with water.  It works well enough on bare copper PC boards to provide a corrosion-resistant coating.

Cheers,
Chuck