reader is slow. The reader log contains the following:
INFO:ord_GetKeyFromOracle: Got Snapshot error (rc=1555), trying to use next RCM
If you are getting errors in the <SID>_log.ord with references to RCM and the capture queue is very large, then you are blowing out a rollback segment on the source
Increase the initial size of the rollback segment or play with optimal setting to make sure the rollback doesnt shrink.