It looks like someone changed the IMC-MC2_TRANS_SUM_OFFSET on July 10th around 23:30:00 UTC.  Was there a reason for this?  The input to the filter bank is off, and the offset is on and set, which seems like it's meant to make the sum look like the IMC is locked with 10W of input power. 

The consequence of this change is that the IMC guardian was unable to recognize that the IMC had lost lock (since it looks at this sum channel to determine if the IMC is locked), and so the loops were still engaged, and the integrator at the top stage of MC2 was just integrating up, railing the top stage actuators of MC2.  Not the end of the world, but not so great either.

I'm reverting the settings back to their nominal values.

I've also added a clause to the is_locked() function for the IMC case that if the power injected into the vacuum is less than 0.1W, assume that the IMC is unlocked - hopefully this will catch situations like this in the future.