I was experimenting with adding/subtracting mortite. A one point while they were playing I put my hand in to check on how much mortite I had on one of the passives and felt all kinds of air moving. From there I figured out that the passives edges had fallen apart. The interesting thing was after a recent source upgrade I still was not getting the sound I wanted. I removed a lot of mortite and wow, what an improvement. I hadn't touched the dampening for years prior to that. Not sure what if any relationship there is. I have blocked the bottom ports on the speakers as a simple way to cancel the passives, or lack of passives. The sound is still great. Though last night during a very loud blast of bass during a movie one of the blocks literally came flying off the speaker. That was a fitting end to a scheme showing an exploding planet.
Still trying to decide whether to do the upgrade or replace/repair the passives. Either way involves some serious work given the weight and size of the speakers.