What does an electronics repair shop need to repair my Almarro 318B?

In the middle of June, I lost one channel in my Almarro 318B. I can give the details of what happened if anyone is interested, but IMO it's not germane to my question. In our 7th largest city in the US there is a laughable paucity of choices for hifi repair. I took it to the one recommended by the only true hifi store in town. I had taken another piece of NAD to them quite a while back with an accompanying bad experience, but there's just no options. I wait a month before the guy gets it on his bench, no problem. For the last 3 weeks I've been checking once a week to see if he's got a diagnostic. Leaving out the details, he doesn't know what's wrong with it. He says there's no information on it, no schematic. There actually is one in the manual (which I left with him precisely for that reason, and to know how to properly locate the input tubes), but apparently it's not detailed enough. I am not knowledgeable in this subject at all, so if he tells me that, I have to take him at his word. That was two weeks ago and I've lost patience. Besides a complete lack of communication, I feel he is or isn't able to figure it out in 3 weeks time. I'll be picking it up tomorrow, looking for another place to take it. There are a couple of alternatives in Austin, one recommended by Whetstone Audio there. What I want to know is exactly how much information does a shop need to do this? I doubt Almarro provided everyone that has successfully fixed one with their "detailed" schematic. Thank you.