Occassionally, this module spontaneously "shifts" the effective time of the common-start used by the TDC. In the past, this shift has been on the order of a few nanoseconds.
This is something that must be monitored by the shift workers, since it is possible for this shift to be large enough to push the S2 signals out-of-range. The short-term solution is then to power-cycle the Fastbus crate, which appears to restore the TDC to a sane state.
A copy of this log entry has been emailed to: rsubedi