Steve, you've now confirmed that the voice coils in all three drivers are burned out, which is rather unusual, unless as you suggest now, maybe they failed over a period of time, rather than simultaneously. What amplification have you been using?
It wouldn't seem that the crossover would have anything to do with this. Even a total failure of the crossover would just have sent treble frequencies to the drivers which they wouldn't reproduce well, but this couldn't cause them to fail.
Considering the amount which replacing all three drivers would run, consider instead using a vertical M2 as the center, which some of our members have done with great satisfaction.
