That's the trouble with so many of the Kodak-era separations- they were made, but not tested. Since they were for the purposes of preservation and not print-making, any errors were not discovered until they attempted to use them for a restoration. That's exactly what happened when they started the "Spartacus" restoration.

There must have been some viable separations of SW at some point, though, otherwise there never would have been any Dye-Transfer prints. I wonder what happened to those seps when the British Technicolor lab finished with them..?

There are some interesting quotes here, from Robert Harris about the possibility of restoration, and the reasons he believes the OOT should be included in the blu-ray release (starting w/post #129):

http://www.hometheaterforum.com/forum/thread/307588/tcfhe-press-release-star-wars-the-complete-saga-blu-ray/120