69 Dart Headlights Issue

Thank you for such a detailed guide. I'm going to walk through this after I finish this switch (if it doesn't solve it).

I don't see any way to disassemble this thing further. I'm going to try cleaning the exterior contacts. Is there a way to pull this apart further?
No and last I knew those switches should be available through "real" auto parts stores. And I agree, you better find out where the water came from