I noticed Jack Ely answered the chromatic repair question, however I did want to make one addition to that list and it is one that the harmonica community should not be without.
Joe Filisko 1313 Colorado Ave Joliet IL 60435-3704 815 725-9095
Not only does he do chromatic repairs, but Joe builds one of the finest custom harmonicas, bar none. He is a renowned and respected harmonica technician, player, and teacher. To throw in a plug, Joe would be one of the first people I would contact for custom work or chromatic repair. Then I would call Dick Gardner.