Thanks again muskratmx.
I naturally followed the link to the official CUPS site for printer drivers and assistance. That's where I subscribed & logged in: http://www.cups.org
Gramps is a genealogy program as you will have gathered - version 18.104.22.168 came from the Linux Mint repository; later versions exist and if you open this one, Help/Manual opens the Manual version 2.9. The gramps website gives information about the rather complex situation concerning their available manuals.
Having opened v 2.9 as above, if you go to the File menu there is an option to Print this file - that's where life became complicated - see my first post.
Now I've printed to file, and printed from that file - with rather better results, so that now I only have to correct a few pages incorrectly inserted - reverse printed upside down.
It might have been better to print to pdf and print from that to begin with - my printer (or CUPS?) evidently doesn't like this type of file, filetype .ps