Thank you for the response.
Apologies for my late response.
As a retired 82-year-old man you are running out of time! Time flies. (The truth is actually you've slowed down)
I had also found your described method.
The .pst file is put in the contacts (Only this computer) but there is no synchronization with the address book.
I have two folders "Contacts (Only this computer)" available! One with a few addresses that I created in the Address Book and the other contains contacts from the previous computer.
By searching the internet I found out that you can move addresses from one folder to another.
This is only possible with a few addresses at the same time. A hell of a job but always better than writing down all the addresses and having to put them back in the address book.
My address book is now complete again.

Next time I'll do it differently. First create a contact in the new address book and then install the "contacts.pst" file using the method described by you. You can then point to the created Contacts folder and the address book is complete.
Thanks again for thinking along.