I have a pair of 4410 studio monitors that I've owned for many years. Yesterday I removed the grilles and noticed that one of the bass speakers is deteriorating. The spongy part where the cone meets the frame seems to be disintegrating. I don't know what has caused this as I have never treated them badly and am the original owner.

Does anyone here know what may have caused this? Is the other one doomed? More importantly, can they be repaired? What would be involved in a repair, any ideas on where to take them in the greater Riverside/San Bernardino area of southern California, and what one might expect to pay for this?

I really like these speakers and would prefer to keep them versus replace them.

Thank you all in advance for any help you can give.
SoCalGal