Refurbishing Avalon Ascent Mk 2


After 25 years of service my Avalon Ascent Mk 2 have started to distort especially with classical piano.  I have isolated the problem to both 2" aluminium-manganese mid drivers.  These, I believe, were built by MB Quart of Germany, now out of business and the part seems unavailable.

I would greatly appreciate any suggestions on how I could bring back these speakers to their former glory. Thanks.

franzschubert
Avalon seem to have no interest in supporting legacy systems they are a different company from the Charlie Hansen days but I can try again.

The crossovers are separate, potted in 50 pounds of epoxy so there is no access to individual components. 
@franzschubert  Assuming that it really is the drivers, this might be something that Bill LeGall at Millersound (http://www.millersound.net/) would be able to help with.

Dick