After the offload of F2 and F3 GAS, I remeasured the TF of GAS filters (fig1 - 5).
F0, F1, F3 and BF GAS seem to be healthy though some overall gain changes can be seen.
However, F2 GAS seems not healthy because high frequency above 2 Hz have low coherence, which might be due to rubbing somewhere.

I offloaded the F2 GAS with the FR.

The height of the F2 keystone (2100um) was close to the mechanical limit (2230um) in the last health check. The height was offloaded to 1900um. The coherence of the transfer function above 2Hz was improved. F2 GAS became healthy.

I checked ETMY BF LVDT with the same manner as reported in klog28451.
Results are as follows and BF H3 primary coil seems broken.

-Port 1-1(Primary coils): these should be around 26-28 ohms according to the documents

1-6 (H1): 28 ohms
2-7 (H2): 25 ohms
3-7 (H3): overflow (more than several Mega ohms)

-Port 1-4 (Secondary coils): these should be also around 25-26 ohms according to the documents

1-6 (H1): 25 ohms
2-7 (H2): 25 ohms
3-8 (H3): 25 ohms

I checked TFs if ETMY, which was measured on May 10th.
Some of TFs are strange, so we need to check them carefully.

Followings are what I noticed.

1. Vertical TFs of the tower changes a lot (fig7-11, 14, and 21-23). I would like to ask Takahashi-san to check them.
2. MNV TF changes a lot (fig26). It seems due to increasing the coupling from pitch DoF.
3. MNV3 TF gain becomes lower (fig35). Since currently MNV3 OSEM INF has again of -0.736, it might be due to this gain. This might cause MNV strange TF.
4. IMR TF gain becomes lower (fig39).
5. Sign of TM TF phases are changed (fig47-51). Dd we make a mistake dueing regluing the magnets?

I performed actuator and center balancing of ETMY to confirm strange MNV TF can be better by sensor/actuator decoupling.
Figure 1 shows the MNV TF after decupling.
MNV TF becomes healthy.

Also, I measured TFs from V1 and V3 coils (fig6: V1, fig7: V3).
Since the gain of V1 becomes smaller, the gain of TF is smaller than before but it is not problematic.
Also, gain of MN V3 is now same as the reference, so the smaller gain, which was measured previously, seems due to the gain change in DGS.

So, MN stage TF seems fine now.

What I did:
1. Photosensor gain (MN_OSEMINF_{H1,H3}_GAIN) was changed to minimize the coupling between MNV and MNP (fig2:before, fig3:current).
2. Actuator balance was performed for reducing V2P coupling (fig4: before, fig5:current).
3. V2Y actuator decoupling was performed (fig6)

Abstract:

I continued ETMY health check at IM stage.
Still we have several issues to be solved.

Detail:

Figure 1 shows TFs from IM roll excitation.
Though the gain of IM roll to IM roll at low frequency seems lower than before (not so clear due to low coherence), I could not confirm the reason.
Anyway, I hope it is not so problematic because IM stage doesn't use for daming roll motion of the suspension.

Then, I found three strage behaviours:
1. Small signal jump in IMH2 photosensor (fig2), which seems ADC glitches because the jump at raw input is just 1cnt or so. So, it doesn't seem problematic.
2. Large glitcies in IMH3 photosensor (fig3). I have no idea what they are at this moment.
3. Photnsensor noise at high frequency (fig4), which cannot be seen if suspension is in SAFE state (fig4: blue:SAFE, red:ISOLATED). After several investigation, I found the noise has large coherence with ACC local servo feedback (fig5). So, I modified the ACC local servo. Old servo has an UGF of 20 Hz and phse margin is only 30 degrees. Since ACC is used only below 0.1 Hz, I changed UGF at 3 Hz and phse margin is about 70 degrees (fig6). After these modification, photosensor noise at high frequency are disappeared.

I made a mistake for fig3.
Attached figure should be fig3 I mentioned in original post.

I confirmed IM H2 glitches comes from ADC glitches.
Figure 1 and 2 show the IM H2 signals when the cable at AA was connected and disconected, respectively.
In both case, the glitches can be seen in the signals, so the problem is between AA to DAC, not inside the vacuum chamber.

I also checked the reason of IM H3 glitches.
Figure 3 shows the IMH1 and IMH3 signals when IMH1 and IMH3 cables were swapped at the satellite box.
Since the glitcy channel was changed to IMH1, the glitch source should be chamber side.

After that, I swapped IMH2 and IMH3 cables at feedthrough port.
Then, I could not find any glitches on both signals for one hour (fig4), though there are small glitches in IM H2 signals coming from ADC glitches.
In addition, even after recovering the swapped cables, glitches seem disappeared for more than 3 hours.
I will investigate further if glitches will happen again.

There seems no glitch in IMH3 photosensor for a week.
I'm not so sure if it is recovered or not but there seems no need to touch the suspension at this moment.