The gyro is "gyrating" again (that was for you, Alastair). I have no access to DTT at the moment but I plugged the gyro signal into the SR785 and it appears to be reading something physical. I tapped on some of the output demod optics to see if I saw peaks, which I did. As soon as I can get into DTT again, I will post a new spectrum.
As an update, we have not produced a real gyro spectrum since having installed the windows. When we tried, we got something that looked unphysically low-noise. The problem is not that we think it is too low-noise to be real, but rather that the last time I realigned the cavity---BEFORE installing the windows---I got a similar too-good-to-be-true spectrum. So, if the noise is indeed this low now, it is not because of the windows but instead due to my rockstar alignment skittles.