Just a warning to other "Tweakers" like me
Upgrading (upgrade.php) after having added tables to dbispconfig database upgrade completes but the database tables are not fully loaded.
For reasons not relevant to this post, I had added a table to the dbispconfig database.
When running the update.php script it completed, but the database was not fully loaded. My "new" table was missing and this breaks mysql and hence the restore is incomplete.
I found update had created a backup in my home directory

, So I removed the new table data from the backup file, emptied all the tables in the database and reloaded from the backup.
All now appears ok.
Note: In future I will create a separate database to hold my kludges!