Earlier today I mounted one of the backups and dragged the Epson folder to the appropriate location on the MacPro. When I attempted to print I got a message stating that the software had been incorrectly installed.
I then installed 10.9.4 again...which, as expected, accomplished nothing.
Then I searched the Support section of the Apple site and found the reference to printer update 2.17. However, when you follow that link you arrive at printer update 2.18. Oops! Thanks, Apple.
Somewhere along the way, prior to installing 2.18 again, the print dialog changed to what I suspect is thte CUPS interface. The print settings section had entries like General 1, General 2, etc. Whatever it was, the prints were then OK. Since I didn't know how I had arrived at that point I went to the next step.
So I downloaded 2.18, performed the installation and the warning went away. Unfortunately, the dark prints came back.
I did not try resetting the printing system. I will try that in an hour or so.
Thanks for all your suggestions. Not having agreement between my monitors and the prints for the first time in years is driving me a little crazy!