Around 14:55 notice H1 range took a step down at 13:37. 

Only obvious change was increase in 500-2000Hz bands via the BLRMS of DARM.  This lead me to look at violin modes and sure enough we had a big line on DARM spectra around 1kHz.  Looking at the Violin Mode medm Screen & DTT, it pointed toward: 

ETMy's MODE 18 (as well as a rung up MODE 20).

Unfortunately, I could not find newer instructions for damping violin modes (I could have sworn Rahul had something new because I remember Ed going through a procedure where he manipulated the VIOLIN_DAMPING guardian node.  The only Violin mode instructions I could find were the old ones Nutsinee wrote up.)  So after searching old alogs & through wikis for a few minutes, I then decided to take action:

• Took VIOLIN_DAMPING to DAMPING_ON_SIMPLE (this took me out of OBSERVING at 15:24). 
• Began tinkering around with mainly the gain and some phase for MODE 18 (but I also tried tinkering with MODE 20.
  • NOTE:  Mode 18 (1000.30Hz) was OFF up to this point (i.e. a gain of 0)
  • NOTE:  Mode 20 (1000.31Hz) was ON with a gain of 1 (and its ndscope was definitely increasing....due to being rung up by Mode18?)
• Made some strides with Mode 18 (not great, but a decrease).  
• Took VIOLIN_DAMPING back to IDLE (no change), and then DAMPING_ON_DC & this seemed to undo what I had been doing!
• Went back to DAMPING_ON_SIMPLE (i.e. started over).
• At this point, TJ came in & I aprised him of the situation.  I mentioned I couldn't find O3 instructions for Damping Violins and he mentioned there was recent work with violins to allow changes while in Observing (so I missed that).
• They were both increase when I handed it off to him, but he has stabilized both modes by taking them to a gains of 0.
• In TJ's hands now!