We had a look at the RIN of the transmission signals TRX and TRY, when the arms were individually locked on IR. If the intensity noise is very bad, then the transmission signals aren't really a good option to use for locking. So, if the RIN is bad, we need to work on our intensity stabilization.
We need to understand what the situation is with the AOM, and why it isn't working as expected, so that we can reinstall it. We also need to decide if we're going to use the SR560 setup, or if the Chas ISS is sufficiently characterized for us to use.
The RIN is certainly bad. Also, I don't know why the Xarm's RIN is worse between 10 Hz and a few hundred Hz than the Yarm.