HP Technical Support offered some advice on how to resolve this issue:
Things to check
1. You should be using the latest DeskWriter printer driver (currently v6.0.3), both drivers are installable from the 6.0.3 disk image.
2. Try a good known set of serial or LocalTalk cabling.
Driver Installation Procedure
Starting with System 7.5.3, the Installers for HP DeskWriter printers require the Extensions Manager be set to "All Extensions OFF" prior to the installation of the new printer driver. Having the shift key down when booting will NOT work.
Specifically with System 7.6, the Extensions Manager should be set to "Mac OS 7.6 Base", prior to running the DeskWriter Installer. After the install has taken place, the Extensions Manager can be placed to any desired settings.
If the printer still does not work, then HP Technical Support suggests checking the printer and cabling. Specifically, you should first ensure that the printer is functional by seeing if it will print a test page. To get a test page, hold down the Select button and then power ON the printer. After the print engine starts moving, release the Select button and a test page should appear.
The test page will print either "RS-422" or "AppleTalk" at the bottom of the page, depending on the configuration. If the test page prints, cabling should be checked next.
This article was published in the 17 June 1997 "Information Alley".