Since we've gotten back from the OFI vent, we've had chunks of time where we struggle with PI's ringing up (attachment1). During that time, we've made changes to filter bank settings and adjusted the max power during our efforts to try and tame them.

Timeline of PI ringups and associated changes (all times in UTC)
August 22-23rd (alog79673)
    - Multiple locklosses from PI24 (lockloss1,lockloss2,lockloss3)
    - Changes made to PI damping (alog79665)
August 24
    - nominal max power setting changed to 61W so as to bypass it for the weekend
August 27 (alog79753)
    - PI31 ringup (no lockloss)
August 31 (alog79836)
    - PI28 & PI29 ring up and cause lockloss
September 02 (alog79860)
    - PI28/29 ring up and caused lockloss
    - nominal max power changed back to 60W
    - PI28/29 ringup causing lockloss
    - PI28/29 ringup causing lockloss
    - PI28/29 ringup causing lockloss
        - These last three lockloss were with 60W
        - These four locklosses all happened one after the other.
September 17
    - PI24 ringup and lockloss
September 21
    - PI24 ringup and lockloss
September 23
    - PI24 ringup and lockloss
September 25
    - PI24 ringup and lockloss
    - PI24 ringup and lockloss
    - PI24 ringup and lockloss

Something weird first noticed by TJ during the 17:52UTC ring up today was that PI24 looked a lot noisier than usual. I looked back at the previous PI24 ringups(attachment2) and noticed that only the ringups from today (September 25th) are this noisy, compared to the other PI24 locklosses we've seen since the vent.
After this latest lockloss, the nominal max power has been increased back up to 61W (alog80295). We are discussing changes to ring heater power since it looks like the max power changes are enough to stop one mode from ringing up, but might be causing the others to start ringing up.