slide damage

I have a scanned image of a 50 yr old slide which has blue patches all over it. Most of it I am able to repair using the clone tool but when it is over a face, I am not having much success with anything I have tried, including playing with various colour combinations.

Can anyone advise a good method to deal with this?

Photo can be viewed at
http://usera.imagecave.com/pebble/

I am using Photoshop Elements 4 on a Mac

Could you post a picture of it? Might get more help that way.