J. Kissel, B. Weaver, J. Warner, C. Vorvick

We lost lock about 2 hours ago, and the cause was excessively rung up violin modes, specifically the 504.8 [Hz] ITMY FL mode (ref LHO aLOG 17610), which are damped by the MODE2 and MODE4 banks of ITMY_L2_DAMP block. I attach a screenshot of the ~hours of adventure. 

To solve the problem, there's no magic bullet unfortunately. While DARM is still locked on RF, we turn on the damping loops one at a time. The "nominal" gains of -100 and 300 for these banks are too large for the current amplitude of the lines, so we have to start with a small gain and work our way up. The attached screenshot shows the progress. I'm hoping to have them reduce enough (roughly equivalent to the current Bounce and Roll mode amplitudes) to move on to low-noise in an hour or so.