Thanks @BassBodfor the Stuart Watson rec, we have corresponded and I'm going to get my tech guy to have a chat with him. At this point the amp has been brought back to the bench, opened up and its contents partially laid out on a piece of plywood...
I'm hoping this comes to a happy end soon.
I'll post when it's up and running. I'm saving my 135 lb Ampeg PR410HLF for it... 🙂