Solution:

If access has been lost due to a service account change, then you can logon as the old service account and provide permission to the new account by going to the view above and then right clicking each queue > Properties > Security tab to add the new account with full permission.

If the old account is no longer accessible, there are two possible remedies:

• The powershell script attached will attempt to give full permission to the FNMS private queues to everyone in the Administrators group.  You can run the script as a local admin and ensure the service account is part of the group (or modify the script to give permission to another group that the service account belongs to).
• Alternatively, you can turn off the Windows MSMQ feature, reboot the machine, and then re-run the config.ps1 script, which will re-enable feature and assign full permission to service account provided to the script.