I believe the best option in this scenario is to contact Bill Legall of Millersound. He is the repair facility for countless folks, including many recognizable high-end audio loudspeaker manufacturers.
If one driver went, most likely, the other has degraded as well. Bill will request you send in both drivers, and he will restore them to as-new status for much less than the cost of replacing the bad one. Both drivers will then be equal to one another, and they will work for many, many years into the future.
