Oh I definitely won't argue that most counter help now days is just about worthless. The local Autozone owner has a thing for young girls and stacks his counter accordingly. Nothing like taking in a starter or alternator and they look at you and ask what the part is?!? But back to the machines, I have not had much luck with any of the stores being able to successfully test anything. Similar to the OP, we lost fire on the fastback. Everyone pointed me to a bad TFI, so I took it into the store to be tested. Yep, tested OK. After several weeks of research and throwing parts at it I finally bought a new TFI and all was good!