NeverarGreat said:
... to correct an almost completely red-shifted frame ... throw everything I could at it in Photoshop.
My general approach is R-G-B histogram manipulation (low-high adjusts to produce known blacks & whites, and gamma adjusts to produce known greys), which wasn't working well with this faded film clip that was also blown-out in the photo (lots of RED artifacts all over, like ants).
Checking the auction's additional photos, I found one where the film & sprocket holes were still clearly delineated (ergo, no blown-out in the photo). That one was fairly simple to de-fade, but by eye (I had no DVD snapshot handy as a proper color target).