If it isn't doing scan to mailbox (hdd is filling over time because they don't delete the jobs when done) then there are only 2 options
The Fix and the stop gap.
Fix = Altboot no data backup no clone to latest firmware
This is not a Connectkey known issue on any firmware, so the issue is this machine specific, corruption or a hardware failure. Corruption can't survive this process, but of course you will have to set up everything all over again from scratch.
Stop gap = Set the mailboxes to delete files older than x amount of days, and set Secure disk image overwrite to happen daily when nobody is there.
