Beginning measurements of IMC Crossovers. 

Not sure why, but I found the IMC locked, but with the top (M1) stage turned OFF, gain sert to zero, with FMs 1 and 2 on. In order to engage M1, I
- turned off FM1 (the boost), turned on inputs and outputs
- used a TRAMP of 20, and ramped to a gain of 1.0 (probably didn't need to go that slow, but I didn't want to blow the lock)
- Turned on the boost filter.

Also found FM9 (CLP300) of M3 LOCK OFF, so I turned that ON.

The LOCK Gains are now [M1,M2,M3] = [+1,+0.2,-300].

Finally, all of the notch filters (FMs 6-10 in M3_ISCINF Bank) were OFF. Turning them on (both the R3 and V3 notches [FMs 6 & 7], the 1st, 2nd, and 3rd harmonic violin mode notches [FMs 8-10] independently) makes the loop unstable, as indicated by the MC2 output at all stages increasing wildly hitting the limiters. We'll have to explore / model that later.

Save the notches, and the factor of 2 difference in M2 and M3 gain, the configuration should be the same as what's at LLO.