HP6980 Duplex Driver in Windows 7
Friday, 08 January 2010 11:53 | Author: Paul | 
I have been searching for months to fix why my HP6980 printer won't print duplex automatically since installing Windows 7 - finally the answer which works for me:
"Do the following: go to the Printers folder, right click on the Deskjet 6980, Printer Properties, Device Settings, Installable options, Duplex unit, set to installed, OK.
If your driver does not support duplexing with the above then go to the Printers folder, right click on the Deskjet 6980, Printer Properties, Advanced, New Driver, Next, HP, click on Windows Update and wait a few minutes for the list to update, HP Deskjet 6980 series (HP), Next, Finish, then if necessary go to Device Settings and set the duplexer to installed."
Taken from HP Support forum.