Electronic Engineers in Chicago may be a relatively close option. I have used them for repairs on recommendation and they know what they're doing.
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I have used Audio Ventures of Waukesha, WI (http://www.audioventures.com/) to great satisfaction for both tube monoblock repair and speaker re-building. I am also familiar with other audio nuts who have used them and been very satisfied, including a manufacturer who brought his personal equipment to them.