Don't know if these suggestions will help, but maybe they will get you on the right track or provide some leads. I would try Audio Consultants on Clark Street. They are supposed to have a pretty good repair department; however, I suppose there is a difference between "repairing" and "refurbishing." But again, they may know of someone who can help.
The other suggestion may be a shot in the dark as well, but Van L. SpeakerWorks on N. Western Avenue. They specialize, as you would expect, in speaker refurbishing, but they have also carry an interesting line of new and used electronics, and they might be able to direct you as well.
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