The restoring of the drivers for B&O speakers is possible and several offers this service in Denmark for about GBP 300 or € 50.
I have used this service several times and normaly the result is exelent. I do a frequency test and a distortion test of the speaker after the driver restoration (and filter component change of coarse), and the speaker is very near the original spec's.
Beolab 5000 - "If another amplifier sounds different then it needs repair!"