Donjr..any reputable repair company can repair your gear on the condition they can obtain the schematic sheets from the manufacturer of the amp or preamp or other component's you have that need repair. Their are certain free audio electronic data services online where you can go to download the schematics on older gear. I have downloaded in the past schematics on older gear just by doing a schematic search on Google. Normally, only authorized repair companies get the schematics but if a company is about to tank, it should be no problem for you or the repair company in your area to obtain the schematics.