Hi James,
we solved this issue (and now facing the next one 
)
We were able to get the correct passwords for the Schema user and Control user from the installation files: KEYDB.XML and CONTROL.XML with the help of SAP Support.
I located the files and forwarded them as an attachment to my incident.
Once we have these credentials in our DBCO then everthing on the database side is working fine.
We now have a different problem with generated tables in LTRC system having incorrect field lengths compared to corresponding MaxDB tables. We have an incident open with LTRC component.
Thanks for the assistance.
Mark.