Good job, baffin. So now you finally understand that MOVs don't WEAR. Or do you?
Your tires wear. Your brakes wear. That's a normal in-service condition the designer fully expects and accounts for. The device still meets spec and performs as intended after significant wear. Your window glass doesn't wear. If it takes a hit, it's either OK or broken. Same with MOVs. That's why they put LEDs on the better ones, so you can tell if they're OK or broken.