OK some pics after i cleaned a layer of dirt and grime off the playfeild. I've never seen Mylar in the flesh, but, i'm pretty sure this machine has been totally mylared, or are all Sterns like this?? Around posts etc. i can see where it has been cut, it's like a type of thin plastic. Stoked the playfield is in awesome shape, no wear expect for a small amount of flipper drag and a few pissy scratches.
Backglass has faded yellow (as Rod71 pointed out), but un-noticable to an untrained eye (like mine) and takes nothing away from the appearance at all i reckon, only a few scratches that are hard to spot also. I'm not going to bother buying a new glass this one looks great, i'll give it a clean.