J. Kissel, J. Driggers, C. Gray 

We've successfully damped the 4735.09 [Hz] violin mode harmonic. The key: the +/- 60deg phase filters in the ETMY_L2_DAMP_MODE9 bank, which we thought were moving the damping control signal phase around the unit circle, was actually not adjusting the phase at this 4.7 [kHz] since they were tuned for the 2nd harmonics at 1 [kHz] (thanks to Jenne who dug into foton to check that these filter made sense). This left us with essentially only 0 [deg] (+ gain) or 180 [deg] (- gain) as options, and neither worked well. 

After rearranging some filters between MODE9 and MODE10 filter banks, Jenne was able to create new phase adjustment filters with 30 [deg] increments for 5 [kHz]. +60 [deg] with a positive gain worked well for the first two orders of magnitude, but we eventually needed to nudge by -30 [deg] once other modes around these frequencies began to be resolved, confusing the error signal. Thus, the final settings that we think will work well:
MODE10: 
gain = +0.02   (we were able to use up to +0.1 while we were trying hard)
FM4       ("100dB")        gain(100,"dB")
FM9       ("+30deg5k")     zpk([0],[28.5238+i*4744.41;28.5238-i*4744.41],1,"n")gain(2.07488e-06)
FM10      ("4735")         gain(100,"dB")*butter("BandPass",4,4734.5,4735.5)gain(120,"dB")

I think all the success I claimed yesterday () was merely by turning on the notch filter in the DARM path and waiting.

I've updated the LHO Violin Mode Wiki, and I've also updated the ISC_LOCK guardian code to ensure this continues to get turned on (specifically I edited the gen_VIOLIN_MODE_DAMPING functional state in the ISC_GEN_STATES.py subfunction that creates VIOLIN_MODE_DAMPING_1 and VIOLIN_MODE_DAMPING_2 in the acquisition sequence).

Unclear if related to Cheryl's reported problems with the fundamentals over night (LHO aLOG 32059). Note the Violin Mode Wiki or the ISC_LOCK guardian have been updated with her changes.