SPID Cleaning/Restoring/Preservation

[LT7A]

I have a truck where the SPID came mostly unglued and the previous owner put it in an envelope with a bunch of other pertinent papers. So, fortunately, I have it. Unfortunately, it's dirty and folded in half. I would like to clean it as well as I can without "experimenting" too much. So I figured I would ask any of you has found something that has worked really well. Also, since it's folded, I'm hoping to flatten it out. And then put it into a clear 5x7 sleeve, semi-permanently mounted to the glove box door.