Work done today, 5 Dec:

• IM1: no change
• IM2: SiC baffle loosened and viton inserted, and baffle screws retightened
• IM3: tightened OSEM bracket bolts, and identified that the top OSEM bracket moved when I was tightening a lower OSEM bracket, recentered OSEMS, then reinstalled the SiC baffle with viton between the baffle and the IM tower
• Shift in top OSEM bracket while tightening the lower OSEM bracket suggests that the OSEM's had more than one stable position (since the top OSEMs remained stable after that shift), which would be an explanation for the alignment shifts seen during O2
• IM4: bias relief for pitch, reinstalled the SiC baffle with viton between the baffle and the IM tower
• Possible mechanical short in the SiC baffle to the IM tower, even after adding viton
• The inner SiC baffle on IM4's baffle is in direct contact with the EQ stop viton, which is a mechanical short, though possibly damped because the EQ stop bumper is viton

Plan for tomorrow:

• if possible in the morning, B&K all IMs

Info for tomorrow, 6 Dec:

• all IMs are ready to be B&K'd to evaluate the damping of the high Q resonant frequency
• on all IMs, the viton was inserted between the IM tower and the SiC baffle
• on all IMs, the bolts holing the SiC baffle have locking washers, though I am unaware of the benefit
• on all IMs, an unbalanced force on the 4 SiC attachment bolts and their locking washers may break the baffle, so please refrain from tightening those bolts if at all possible
• on all IMs, if it becomes necessary to tighten the SiC baffle attachment bolts to further damp the Q of the resonant frequency, do so with small adjustments that are spread evenly to all 4 bolts, to avoid putting uneven stress on the SiC baffle

- Cheryl, Sheila, Hugh