77FN said:

Some of the ON was destroyed for good too, according to this article:

http://arstechnica.com/gaming/2013/09/once-lost-star-wars-related-short-to-screen-for-the-first-time-in-33-years/3/

"Tanaka: I remember when we were working on the Star Wars restoration, that was a different process. I think we optically recreated interpositives. But in order to do this, it went through some kind of warm chemical bath cleansing. The weird thing about Star Wars was that it was made up of different film stocks, so it went through this bath and they didn’t know what would come out on the other end...

Tanaka: There’s a space battle shot and a close-up on Hans Solo, and the original negative is coming out of this cleaning solution and it’s just acetate.

Parker: It’s all clear. Oh no, did the bath dissolve it?

Tanaka: Yeah, it dissolved it, depending on the film stock."

I get the impression that they are referring to the shot where Han Solo is in the turret gunner seat and the frame is rocked side-to-side as an optically-printed animated effect as the attacking TIE Fighters blast away at the Millennium Falcon. Pretty sure that's how it plays in the GOUT, anyway. That shot could have been printed to CRI from camera negative and then the CRI subsequently faded away to clear years before it even reached that cleaning bath. If that's the case, the actual OCN for that shot - without the animated shake - might have been in the same faded-but-usable condition as much as the rest of the OCN.