Yes, shellac turns a weird powdery brown when it fails. The alligator flakes on Rodney's machine were likely brown around the edges... I also have a machine here that the shellac has failed on and it's got that brown powdery film on it. I may take it on one day, but it's a real project and not a machine I've bonded with (about a 1920s 99 that requires massive electrical, mechanical and appearance work.)
Rodney, I was once looking for a good photo of an alligatored machine and had no success. You don't happen to have one, or the willingness to make one, would you?