We've known for a while now that we can move the ITMs (ITMX pitch goes down by several urad, iTMY up by about 1 urad) to get a recycling gain of 32-33, but we've seen that the IFO isn't stable like this.  Elli looked into two sudden lockloss that happened after we tuned up the recycling gain on Thursday, (17921 ) and saw that something is going wrong in the MICH loops (both LSC and ASC) before the lockloss.  Yesterday, Gabriele Evan and I noticed that the MICH LSC loop was marginal in the final low noise state, Gabriele designed a filter (called comp, in FM10 of the MICH bank.) to make the loop more stable. (before and after screen shot atached)

Today I tried a few more times to increase the recycling gain, we were locked for about 20 minutes with a recycling gain of 32.5, but most of the day we have had unexplained locklosses and difficulty locking, both with and without improved recycling gain.  I've edited the guardian to request 10 Watts instead of 15 and leave things trying to lock.