First I tried implementing the changes Sheila suggested for SRC2 P, then remeasured DHARD P with a gain of -60.  The result is the black line in attachment one.

Jenne and Satoshi rebalanced the arm ASC output matrices in alog 46707.  Unfortunately in DARM_TO_RF we hardcoded the old DHARD outrix (attachment two), and this is likely how we've been operating ever since Wednesday morning.  I was able to change the outrix in lock no problem.  I lost lock when trying to redo the DHARD P measurement from before, but from the one average I got it seems like this did not make a difference to our 1 Hz DHARD P gain margin.

I spent some time gathering TFs related to the DHARD P loop to try and figure out who is the most relevant culprit is at 1 Hz.  This arose from a suspicion about the radiation pressure compensation and regular filters sum, but this cannot be the issue since the RPC digital filters barely affect us with -60 gain on the regular filters.
Attachment three shows the ASC-DHARD_P and ASC-RPC_DHARD_P filters, alongside the measured OLG I took, and a quad sus L2Pitch->L3Pitch TF and L3Pitch->L3Pitch TF stolen from Hang.
The OLG is well-colored by the total digital filter TF, except around 1 Hz.

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Twice this evening I lost lock in POWER_30W, and when the IFO went down the IMC could not relock itself.  It just went to from LOCKED->DOWN->ACQUIRE and continually failed to acquire for up to twenty minutes.  This only happens when the IMC is super calm, so I added an automatic toggling of the MC2 M1 L2L DriveAlign offset every 15 seconds in the IMC_LOCK guardian.  Not clear if this helped, but probably did not hurt.

Damped ITMX Mode 2.  Rotated +60 degrees from where the guardian put it.  The violin modes guardian does not tolerate dissent, so I had to pause it.
- The mode bounced back and killed the lock.  I tried damping it for about an hour with no success.
- In the next lock I just reduced the gain from -5 to -1 with the same phase (-60 degs), this seems to have helped, but the mode is damping at a glacial pace...