What is this white crystalized substance?
 

Finally starting to dig into my 1956 Packard Bell and the yoke has this white junk on it. Is it some sort of corrosion and how should I treat it?

Looks like "knob fungus" some plastics like to form it. It's harmless electrically, and on some plastics it can be cleaned safely with a soak in windex (some plastics are harmed by it though)...Don't soak the coils.

Yoke cover plastic of the 50's and early 60's has a tendency to become brittle and disintegrate so be careful with it, and be wary that this could be a manifestation of the beginnings of that.

Interesting. Thank you!

Could be an oxide of magnesium, zinc, or tin... or some mix....
battery activity of 2 metals in contact with each other...

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