they will not "mend" per se...
the foam rings "surrounds" will simply be replaced.
as others may have mentioned, it would also be a good time to consider replacing the caps in the crossover.
as they seem to have had little use, they should otherwise check out fine, and you can enjoy them for another 30 years!
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i should also mention from your op -that unless there is a definitive fault w/ the driver(s) -there should be no reason to go the expense of replacing. the re-foaming (should not be very expensive) and if you choose -the re-capping (could be pricey -as there is some benchwork) should be sufficient. btw, if you are a "crafty type" you may well be able to handle the re-foam yourself. it is actually rather fun. there are some good threads on this regarding doing the job -complete w/ photos!
look here:http://forum.beoworld.org/forums/thread/40162.aspx
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