Bottleneck Headphone Amp Repair

My son has a Bottlehead Headphone Amp I gave him as a gift and he assembled. His first project. It operated for some time but has ceased to operate. does anyone know any techs in the bay area that could inspect and repair the amp. He is feeling a little intimidated by troubleshooting the amp etc. I know that bottlehead provides this service but they seem to have placed that service on hold for the time being or we would go down that avenue. He has another one that is ok but way prefers the bottlehead. Its made him realize there is a difference. Thanks for any assistance any of you can provide.