I had a look at the damping trends of ETMX violin mode 9 which was ringing up for 2 consecutive nights (as reported by Jeff B in his LHO alog 47969, ) and bumping the IFO into commissioning. This mode sits at 516.781 Hz, which is very near to ETMX mode 7 which sits at 516.678 Hz. I compared the ndscope (figure shown below) and found that ETMX mode 9 rings up very high when Guardian chooses not to damp it - at the same time ETMX mode 7 is being continuously damped. However, once damping is applied to both the modes, ETMX-mode 9 decreases significantly over time.

I would encourage on-shift operators to apply damping to ETMX mode 9 (GAIN - negative3) even if guardian chooses to switch it off (this usually happens at the beginning of the lock).