Can Alps switchplates be cleaned?

[just_add_coffee]

I'm working on a Northgate Omnikey Ultra with white Alps switches. I had gotten the board without a cable, but super cheap, and Orihalcon was able to custom build an awesome Soarer's Converter cable for it.

I discovered that 23 switches do not work. In the course of troubleshooting, I decided to remove a plastic rivet on a corner of the switchplate, and was able to swivel the contact out of the way to take a look inside.

There was copious amounts of corrosion and gunk in there, removable with a pencil eraser, and the same was true of two other switches that I mutilated.

Is there a way to clean these without having to break apart the switchplates? Any liquid that I can dunk them into? Vinegar? Isopropyl Alcohol? Russian Imperial Stout? Or is replacing the switches entirely the only remedy?