errors with LS421de and backups

[MDCalp]

Hello.  I have two identical NAS with one identical drive in each (~ 3TB each).  Both have latest firmware (1.3).  'A' is main drive, 'B' is the backup.
All applications are turned off and no web-access turned on.  SMB is enabled for both drives.
HD 'A' is about 90% full and 65% on B.  (they are different because data on A has been accumulating without copying to B for some time)
I am cloning (overwrite differential) A to B and it was working for a while, but it stopped a while back with errors and there is too little information to figure out the problem.
-I have a blinking red LED on the device (5 slow, 4 fast) and an error in the browser interface that says 'backup job failed' and the Backup section says 'Error/Standing By'.
-I have tried a cold reboot, tweaking the backup settings (which changes the 'Error/Standing By' message to just 'Standing by').
-I've gone through most of the settings and can't find any differences that weren't deliberate (when it was still  working)

If I do an 'immediate' backup it's says 'done' right away and the 'error/' part of the message goes away but no data is transferred and the LED still blinks red.

How do I make that red LED go away!  And is there any more info about the failure?  Because NAS to NAS backup supposedly have no logs there is nothing for me to investigate the problem.

Thanks
matt

[ianhouser]

I'm having the same issue. Did you ever get this resolved? I'm considering pulling out the drive and running it through usb for backups to avoid this weird problem. You'd think a drive in the bay would be able to back up without issue.