Dan, Vincent, and I measured the particulars of the SUS, SEI, and ISI cable shields feeding into BSC8.  In summary, there are two geophone cables that are showing anomalous grounds on the shields, but all other cables are fine.  The geophone cables are likely the same issue we saw in the end station, so Vincent and Jim are going to tighten the strain relief screws on the d-subs that serve the geophones, but this can't be done until tomorrow.  If this doesn't fix the problem, there will be some head scratching.