Help! CUPS in Kubuntu is driving me crazy

[D. R. Evans]

OK; I got it working, by a horrible hack:
  I copied everything from a working Mdv install.
Bingo, it all now works. I don't know what the difference is; I did
look at some of the obvious places, but the files from the Kubuntu
installation all looked sensible.

The fact that jobs actually got sent to the printer, but then printed
incorrectly, seemed to scream "the PPD file is broken", but it wasn't.
So I am completely out of ideas as to what was going on. Pity, because
I like to be able to post solutions, but "copy from a working
installation" is not a very viable solution :-)

This entire experience sort-of reminded me of the state of Linux
printing five years ago :-( I hate that kind of time-travel.