SilverWook said:
The Disney clips were cut from all home video releases, and even prints of SPFX.
16mm and Super 8 versions of The Black Hole and Mary Poppins were purchased to restore that segment, and a Youtube video of an unedited UK broadcast was going to patch Mark Hamill's narration.
I have two beta recordings of the original broadcast of SPFX if they'd be of any use in a preservation.