I adjsuted the gain of the SRCLFF filter while running a SRCL injection to reduce the coupling to DARM. (Screenshot attached). I've add the gain of 1.15 to the lscparams file so that the guardian will use this gain in future locks.
This is similar to what Gabriele did in 77492, and the calibration of traces in his screenshot is the same as mine (they are made using the same template.) Gabriele's "new FF" (red trace, -160 dB at 30 Hz) is giving worse performance today, shown by the blue trace "Old FF" in my plot, (-145dB at 30 Hz).
So it seems the SRCL FF gain that we need has changed quite a bit. This may be because of the OMC alignment offsets that Jennie Wright added to improve our optical gain in 77543