Not a full machine... but have had my Astro "Black Sheep Squadron" few a couple years now; with a backglass that was flaking most all the dark blue.
This week, I grabbed what appears to be a NOS backglass off eBay. It was framed long ago and pulled from an estate sale of an old eccentric military guy.
The black marks on the back, are from where the framing springs held the cardboard in behind it. A few of those spring-spot have peeled a tiny bit of paint... but it's all black edging... so will be easy to touch up later.
Best I can tell... it was never installed in a game. It has an ever so slight, but long scratch on the left side... so the glass was probably never used, put off the to side and eventually ended up in this frame.
It's overall way better condition then my original glass. (especially that annoying spot right between her cleavage. LOL)