Thank you all for the feedback. After multiple calls and e-mails to AquaHot and Tom Johnson including an hour long visit today with the tech, the leak is not in the copper wrap. Apparently, the tank has a leak, presumably along a seam somewhere. This is by process of elimination as the unit still needs to be removed and even then we wont know the precise location of the leak since the tank is wrapped in copper piping so you can't even see the tank. There is a slim chance that it may be a lose/tight fitting but I don't believe I'm going to get that lucky. AquaHot's "replacement part" is a new system - tank, diesel burner, indicator panel, etc. for a grand total of approx $12,500 installed.
Are we having fun yet?