Roger,
This client brought in this seat cushion. He has no idea what happened to it, but it looks like burns or something else splattered on it like a solvent or glue? The leather is dark and hard and is thicker form puckering up. I can feel it form the back side. There are a lot of very small spot around these 3 areas that did not pucker and that is why I think something got on it and hopefully it is not burned.
I was going to test prep cleaners on the side to insure they were safe to use. This is an aniline that has a lot of the natural marking still in it.

How would you proceed to try to restore it?

Name:  100_2991.JPG
Views: 215
Size:  4.30 MB
1-25A Looks like a burn but I'm hoping it is glue or something else that caused it to pucker up and darken.

Name:  100_2992.JPG
Views: 211
Size:  3.42 MB
1-25B Another spot

Name:  100_2995.JPG
Views: 163
Size:  4.14 MB
1-25C Another area