PBase

I am trying to make good pictures from old Kodachrome slides that have suffered from being left in a garage for forty-something years. Please somebody look at the example (and the story) at http://www.pbase.com/image/152140559 and tell me how to fix just one of the problems. And is there a way to physically get the mould off the slides without taking the emulsion too?

If you can, open the image in camera raw. Go to Hue/Saturation/Luminance. In Saturation reduce both the red and the orange by 100%.
Proceed to Luminance and do the same, reduce both the red and orange channels by 100%. I tried this on your image using Photoshop cc and the results were quite nice. This might not be all you want to do to the image but its a beginning. Best of Wishes - Bob Waggoner

When I took a second look I noticed that their was still some discoloration along the bottom of the image. Using a soft brush and the clone tool
this was also fixed. Hope this helps