How to connect a new installed Tomcat-Bonita server to an existing Bonita database

We have an operational Windows-Tomcat7/Bonita7.2.2 (community) installation, configured for Oracle11g
All good. It has been running a process successfully for a couple of years. Hundreds of Cases open.

Unfortunately we need to replace the VM that is hosting the Tomcat/Bonita server in the next 2 weeks.
Of course we want to keep the existing database and Processes/Cases/etc.

This sounds like it should be very do-able, but every time we try it fails.
- After install and DB configuration the Tomcat/Bonita service will start ok
- But on the portal we get
“The current node has not been started yet. Method PlatformAPI.startNode() must be called previously”
or similar.

Our guess is that 'normally' upon first startup Bonita sets up the database and creates various Tenant files on the server.
However in our case it sees that the database is already setup so does nothing, and we end up with no Tenant files.

We have of course tried copying various selections of Tenant files from the existing VM but nothing has been successful to date.

Help gratefully received...