Window hinge

I am trying to repair the windows from my '53 Rod and Reel but have come upon a stumbling block. I can't seem to figure out how to replace the rusted tiny hinges that let the windows swing open. They seem to be either tack welded or possibly pop riveted into place. It's hard to tell they are so rusted. Also, not sure where to find replacements? Could I just use a similar tiny piano hinge? Anyone have experience?

Here is a picture of what I'm dealing with:
www.flickr.com/photos/150754054@N05/34896383650/in/dateposted-public/