You may check with Steve Huntley of Great Northern Sound. They do excellent mods to ARC gear (Steve used to work for ARC). Don't know about repairs, but their Standard upgrade is around $750, and would be money better spent than a simple repair, if the ailing components happen to fall within what is included. I had them do a Standard Upgrade to my LS-2B and was very happy with the results. Steve may be able to point you in the right direction for a good repair resource.
Marco
Marco