Yeah, my body is really clean apart from this problem. I'm thinking ahead to having to buy a second body at some point. I'm leaning toward a good late-model 500CM. I don't know which of the later models did or did not have the palpas lining.
Thanks for the tips on removing the old lining. I can see a day when I will have to do that, which will make my 503cx body become my backup. Not something I'm looking forward to doing. I don't like the idea of selling it to someone as-is unless they know exactly what they're getting. Wish I had known beforehand, but it wasn't a problem when I bought it used a few years ago.