New ribbon installed thanks to really quick service from Magnepan and just to play it safe the sub is moved in front of the r/h speaker - the Maggie Magic is back!
I'm not sure what caused the damage and not a peep from Magnepan - I don't think I was driving the amps into clipping but I'm the third owner so who knows what kind of abuse they went through.
I do know they went through a divorce and ended up being stashed in the ex-wife's garage! If only these speakers could talk...
What I heard from Magnepan is that they'll last essentially forever at typical listening levels, but if you play them at very high levels, they'll eventually suffer metal fatigue. And, of course, they can always be damaged in other ways -- the fact that only one of your ribbons was stretched suggests to me that something catastrophic happened to it. Or maybe they had both stretched, and one broke, and the previous owner just replaced the one that had broken?