That's the shellac that's gone bad, not rust I think. It gets brown and yellow with age. There may be some rust spots, but the alligator look is the shellac cracking. There are ways to make it look better, but it takes a lot of time and elbow grease. I've redone one machine and although it doesn't look 100%, it's much improved. There should be a tutorial or sticky on the top of the Vintage Section on how to French Polish or fix the shellac by Glenn.