Thank you, all. I didn't seem to be making mych headway, and finally resorted to re-running the set of instructions regarding installing the foomatic driver - as spelt out by mark911 -
https://mark911.wordpress.com/2014/1.../#comment-1378
And this time, miraculously - I'm sure there is a sound technical reason there, but it seems like a miracle to me - it worked! I have the use of my printer again.
Am deeply grateful for this resource of helpful fellow-users.