Called Epson, with trepidation because I have been hearing that the quality of their support has been fading over the years, but had a good experience this time. Even though the tech called himself "Dave" he was obviously in India, or an Indian working somewhere else, but he was understandable. He was overly reliant on phrases like "Thank you for that information" but not impossible and we resolved the issue.
I had to completely remove all printer parts including the Epson Printers in the Library/Receipts folder, the two Epson .plist files in the Preferences folder and everything in the Epson folder in the Library/Printers folder. Then the reinstallation was successful. Still, in the Printer Setup Utility, I had to ignore the printer that showed up initially and choose More Printers, then the popup for Epson Firewire (yours may be Epson USB or Epson Ethernet) and only then did the correct driver show up and the install finish successfully. Sheesh.
The secret phone number to call them is 562-276-1300, which is not listed anywhere on their site.