Thanks, Tesla, for the details.

I didn't know there were 2-gang 'handy' boxes, nor was I aware of the connectors you mention.

That's an interesting tip about the carpenters' square.

I suppose we all have our own habits. I do agree with the GFCI upgrade.

"Surgical" gloves for shock protection? Well, that's just plain silly - especially when you've already traced & killed one circuit.