The vault footage is presented in a rather outdated SD transfer. None of it is in HD, even on the blu-ray. There are lots of digital artifacts. So that makes doing any color correction or restoration much more difficult because so much resolution and color information just isn’t there. I don’t know if they intentionally used substandard transfers to specifically prevent fans from restoring it into the episodes, or if they were just too cheap to make new HD transfers. I’m betting it’s the latter reason. Either way, it’s a huge shame because even faded 35mm footage would have looked much better with a modern HD transfer.