Andy, following work from TJ and Josh

My best guess for the cause of the extreme glitchiness is an electronic problem in the ETMY L2 driver. I think TJ and Josh were thinking the same thing, but I don't want to speak for them.

We've been seeing the glitchiness get worse and worse at LHO for at least a week. These are short glitches, and now they are loud and frequent (once every few minutes at least). The humidity has been dropping as the weather gets cold, and last winter Robert and others showed that was correlated with increases in these kinds of glitches.

We also see that the only associated channels are the ETMY L2 noisemons. These do see the drive signal, so they will show glitches whenever DARM does. But these are very loud. And I quickly developed some code to measure a transfer function from a few weeks ago, and use that to subtract out the drive signal. The subtraction seems to work well, but the glitches get shorter, sharper, and louder.

So my hypothesis would be that the low humidity is exacerbating an electronics problem in the ETMY L2 driver, maybe due to sparking. While LLO is down, would it be possible to replace the driver with a spare, or at least try to diagnose whether it is working properly?