Hi Gary!
Before making the registry changes, i would suggest you to follow the steps mentioned in the same technote.
1 Verify if any emails are quarantined. Those mails need to be excluded from the backup.
2. If any users are selected for backup whose mailboxes no longer exist. Deselect these users from backup.
3. Stop Antivirus services during backup window.
4. If using Advance Open File Option (AOFO) for Exchange backup, uncheck it.
5. Verify if the option Enable single instance backup for message attachments
(for mailbox and public folder backups only) is enabled. If yes, uncheck it and verify the results.
Thanks and regards,
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