CPFB905

iSeries Navigator message monitor failing on endpoint system

After years of working very well, iSeries Nagivator (Ops Nav) refuses to monitor messags on an endpoint iSeries.  This is a recent development.  Its been working just fine on the endpoint in question for the last 3+ years.  The QYPSJSVR job log shows CPFB904 and CPFB905.  Both are running V5R4...