Reduced the drive on the transfer function for HEPI in the 500 to 1000 hz band.  We've experienced a trip for the L4C everytime the TFs would get to the V4 drive.  I can't find an unusual drive (DC level) here relative to the other drives nor an obvious L4C response difference--the L4Cs all look the same to back ground input and the Actuators all displace the IPSs about the same.  The corner 4 L4Cs both H & V do seem to respond more greatly to all the drives than the other corners do; but the others do have varying levels of response to the drive on the different corners.  The response to V4 drive at V4 is just the strongest.  I reduced the drive to 0.5 (from standard 1.0) and it made it through.  I increased it to 0.75 and it tripped but only on the second iteration.  So I'm running the TFs now with this mod (gain=0.5) from previous chamber commissions.  Maybe there is a loose bolt somewhere?

Attached is a plot showing the L4C responses as the TFs go through the drives.  The Drives run H1 H2 H3 H4 V1 V2 V3 V4 although I've got them jumbled in the plot.  But you can use this to see how every corner is responding to the 8 local drives.  The WD trips as soon as V4 starts so you can work back through the plots to get your bearings of where things start.  It is interesting when you realise the response on a corner/HorV isn't necessarily the largest when that corner/HorV is driving.  For instance, V2 responds more greatly to the H2 drive than it does to the V2 drive.