Windshield Frame Nut

[JohnB15632]

I am working on restoring an original windshield frame. It requires a lot of work. One thing I am looking at is the windshield frame nut.

How is the nut installed? Is it pressed into the frame? Can it be removed?
How should I install a new nut?

Or, should I just sandblast it along with the rest of the frame?

Thanks,