Sheila, Matt, Corey, Elenna

I reverted the IM2 and IM3 osem positions in order to bring the beam on IM4 trans QPD back to its position before the mystery shift reported in alog 85486. I started by moving IM2 pitch, and noticed that bringing it back towards its previous position did help return the beam on IM4 trans to its previous spot. It was also very largely cross coupled with yaw, and shifted the yaw position slightly as well. I then moved IM3 pitch and further brought the pitch offset on IM4 trans back. I tried adjusting IM2 and 3 yaw slightly, but the adjustments to bring the yaw osems back did not correspond with returning the yaw IM4 trans position to the previous one. Overall, the shif tin yaw position is very small, so I chose to not make any more moves in yaw.

Corey reran input alignment, and I moved PR2 and IM4 by hand significantly in pitch (tens of microradians for both) to get the lock to catch.

While we locked, I reset the POP A offsets to well align PRM to the full lock alignment. This is SDFed in safe, but will be an observe diff too.

The attached ndscope shows the movement that I made. The y markers on the osem plots indicate where the suspensions were before the mystery shift. Note: IM1 also shows movement, but I chose not to adjust it.