It's usually the tweeter panels that get smoked (first) -- as I am sure you know.
My pair were a lucky find. They're late model 57s, and they've never been rebuilt. They're in good condition, but overdue for a refresh.
As an aside, by sheer coincidence, I live less than a half-hour away from Sheldon Stokes.
ESL-57s are amazing but hard to live with loudspeakers, being insensitive, hard to drive
and intolerant of too much power. Plus they have terrible vertical treble dispersion. Everyone should spend some quality time listening to a pair, though, IMO.