[sdiy] cleaning corroded solder lugs?

[Michael Zacherl]

Hi, I'm modifying a module and have to change the connections on an APEM toggle switch.
After all this years it appears that the free solder lugs got heavily corroded.
Since they are all black I assume the lugs are originally silver-coated, which eventually got oxidised.
So scraping the lugs off (with, say, a nail-file) is presumably a bad idea.
What can I do to get a good solder joint again?
I remember my granny (decades ago, though) cleaning the table silver with some solvent,
but that's not easily applicable for this switch, if at all.
Also, to prevent this to happen again, would it be a good idea to put solder onto the unused new lugs?
This would be replaced easily for maintenance or modification.
thanks, Michael.