Today I REPOSITIONED THE SEISMOMETERS in order to triangulate noise sources (as Rana suggested).
I re-levelled all of them, locked them, and turned them on. They should be located out of sight, but just in case:
GUR 1 IS DOWN THE X-ARM, behind the interferometer.
GUR 2 IS BETWEEN THE TWO ARMS, BEHIND THE CABLE TRAP THAT RUNS PARALLEL TO THE X-ARM.
STS 1 IS DOWN THE Y-ARM behind the interferometer.
I'll wait a day for them to stabilize (continuing to reset STS-1 every hour or so) and then begin taking data tomorrow morning, depending on the condition of the signal.
Ideally, I'd like a few days' worth of data, so I'll update when I've changed the configuration back to the way it was prior.