Yellowing on old poloroid

[Pipsmom]

I've been playing around with this old photo( practice piece, not a client)......looks like possiable a old poloid that's fading and possiable a chemical breakdown happening on 1/3 of the picture
I tried all the usual methods and then some.....hue/sat, levels, curves, filters, etc. .....
Its got me stumped.......
What do I need to know and practice using to remove this kind of damage ?
How do you approach this in a work flow?

 

[colleague]

here is what I did ( see PSD )

1- make level-adjustment layer and select black point - white point - grey point
2- make level adjustment layer , but now with only a rectangle selected area
3- there was still a yellow toning , so I filled a layer with yellow,
inverted the layer and put on mode 'color' and play with opacity
4- again a level adjustment-layer because it does not look right
5- working with layers on mode 'color' and brush the wanted colors
you can always adjust the color / saturation and see what works best
6- dodge and burn on a layer filled with 50% grey and mode 'linear light'


https://www.dropbox.com/s/cesdjkl594v56m7/yellowing.psd?dl=0

 

[Pipsmom]

That's why I love this site, friendly people always willing to break it down for newbys to learn....
Thank you for the steps and the knowledge to practice this Colleague
Catch it...Just sent you a hug,