The MC seemed to be losing lock recently quite a bit. I noticed that the PC Drive RMS signal was red.
This means that the high frequency drive to the Pockels cell was too high by a factor of 2-3 and sometimes saturating and breaking the lock.
I fiddled with the gains on the FSS screen until this value went down. It looks like there is some kind of high Q oscillation; it takes a couple minutes for the PC Drive RMS to settle to its new position after changing the gains.
The attached trend plot show the last 2 hours. The mean is now back to ~1 V and seems OK. We should really examine the FSS or MC error point spectra with the RF analyzer while exploring this gain space.