I have made SOME progress.
To remove the possibility of problems from older versions of Dorico I went
Applications> and used move to bin on Dorico 3.5 folder, Dorico 4 folder, Dorico 5 folder.
I then went Finder>Go>Go To Folder and input
/Library/Application Support / Steinberg
there were folders for Content , Dorico 2, Dorico 3, Dorico 3.5, Dorico 4, Dorico 5, and Dorico 6, HALion and HALion Sonic SE
I used “move to bin” on Dorico 2, Dorico 3, Dorico 3.5, Dorico 4, Dorico 5, and the HALion folders.
I shut down the MacBook Pro and restarted
I then got a message
"Dorico’s automatic playback template makes optimal use of the supported sound content, including automatically configuring new sounds when they are installed.
Do you want to use this playback template by default in new projects?"
I chose Use Auto Playback Template.
When I opened Dorico >Preferences it had HALion showing which I changed to HALion Sonic.
It was looking good - until I tried playing back a test project (just something short and simple)
The project has Flute, Piccolo, A. Sax, B.Sax, Bassoon, Fr Horn, Piano, Violin, Viola.
No sounds except from Fr Horn.
The end point map is attached above.
So - First obvious question - was it a mistake to delete the HALiuon folder ? and if so how do I restore it?
Second question - if the lack of sounds is not associated with deleting the HALion folder (and I note I do not get any errors about HALion 6), what is the cause of no sound - and please, what to do to make the instruments sound?
UPDATE - when I look Play > select Alto Sax > I see CC11 - where I was expecting some ref to a sound.
Thanks