Keep trying those plugs, Jim, until the lightbulb comes on.

Based on the florid castings of those ancient Weston electrical meters, it wouldn't be surprising to learn that the patch panel was a castoff from some power plant or such, donated to the university to further higher education (and retire the fossilized switchgear). But hand-patching lines to loads, like we used to do for theatrical lighting circuits pre-solid state, isn't for the faint of heart, especially at some of those voltages! Rubber-soled footwear, please, and keep your left hand (the heart side) in your pants pocket, lad, if you're hoping to live long enough to earn that MSEE.

One has two bites out of it, the other is completely gone. I imagine it might have to do with a heavy plug in an upper row being pulled out, up and away.