Most transfer functions (IP, GAS, BF, MN) look okay but there're a few changes:
Resonance frequencies of the L and T modes at the IP changed, see Fig. 1-2 (refs are old TFs measured previously). But these are not major concerns.
Some transfer functions in GAS DoFs look different (Fig. 3-5). In particular, one GAS mode changed from 2 Hz to around 1.6 Hz.
For F0, the overall gain has changed with a significant reduction at lower frequencies while having a worsened coil to LVDT coupling at higher frequencies.
This could explain why the F0/F1 loop injects excessive noise at higher frequencies with the control engaged. They have to be reworked.
Ushiba-san suspected a change in the BF yaw transfer function because of the damper ring adjustment.
However, the transfer function looks roughly the same as before and the old control should work fine.

With Dan Chen.

We've obtained a flash at the POS REFL PD.
Here's what I've done on the suspensions.

I've reworked F0-F2 GAS control and they worked fine now.
See Fig 1-6 for transfer function models and OLTFs.

The current MN to TM DC control doesn't work well with the 60 mHz oscillation for some reason and it actually amplifies the oscillation.
As a temporary solution, I reduced the gain by 10 times, moving back the UGF from 0.1 Hz to 0.01 Hz.
I've also put a notch at 60 mHz, hoping to reduce the interaction between the 60 mHz and the DC control.
When the optical lever is in range, the MN to DC control works well for steering the mirror in yaw but the oscillation is persistent.
It naturally damps out so it's likely not excited by some external source. But it takes hours for it to reduce to something say 0.1 peak-to-peak normalized QPD readout (assuming ~100 urad/count, this converts to 10 urad peak-to-peak).
I have a feeling that this mode was excited by large yaw adjustment, like the transient of the BF yaw DC control, or BF yaw pico motor control.
This situation is unavoidable since the BF yaw is currently far from "zero", sitting at -2600 urad when it's not controlled. And, it couldn't be offloaded using the F0 yaw stepper motor (we might try again later).
Currently, I don't think there's an easy solution for this 60 mHz mode for now if it ever gets excited again except using an external optical lever at the MN stage, like what was done in IX.
Anyway, this oscillation may be acceptable for PCal work so we may be able to proceed.

With all controls manually engaged, we were able to steer the ETMY.
We first checked if the old optical lever reference coarsely aligned the reflection beam.
We again made an iris for the duct at EYA using aluminium foil and moved the ETMY in yaw. We did see a reflected beam moving horizontally so the optical lever reference was not bad.
We move the ETMY back to the original position and removed the foil, but we can't see any changes in the POS REFL PD.
We tried scanning ETMY in pitch and yaw but still nothing.
Then we decided to go back to the center area and look for the reflected beam but we couldn't identify the reflected beam from ETMY.
After that, we tried to scan ETMY in yaw by large amount again and with pure luck, we saw a single flash.
We then identify a good yaw position and put it to the set point. We tried to optimize the pitch as well but it's difficult as the 60 mHz keeps misaligning yaw and we can only see flashes.
In the end, we settled on a setpoint (SDF shown in Fig. 7)

K1:VIS-ETMY_TM_SET_P_OFFSET: 0.15
K1:VIS-ETMY_TM_SET_Y_OFFSET: -0.56

Fig. 8 Shows the flashes with the TM oplev readout. (note the REFL output sits at ~0.6 and goes up to ~0.8 when the ETMY is aligned)