About 2 hours ago the EX ISI started ringing up again. As the situation was getting worse over the last few minutes, I decided it was time to switch blends. Attached plot shows the StripTool I was watching with the EX CPS locations and IMC-F (the gray trace). I switched the Y DOF blend first (green), it changed smoothly, but didn't reduce the motion. Then I changed the X blend (blue), which settled things down pretty much immediately. I thought it was interesting that IMC-F seemed to lead the swings of the ISI, ie IMC-F seemed to change direction a little before the ISI did. Don't know what that means, but interesting.

I add for the operators: If an ISI is ringing up, and you change the beam direction blend to the 90 blends (X for EX, Y for EY), you should change the perpendicular blend as well. ASC probably doesn't care, ALS doesn't, but 20 micron motion of the tables is bad just on principle.