Thanks for the quick reply. I see that the printer info put into the "Product" box disappeared. Printers are an HP 9800, connected to USB 1, and a Canon i9900 to USB 2.
The Canon suddenly started working again!
The HP 9800 had disappeared from USB 1 and reinstalled it and it is now working so I guess that was a separate problem..
I wish that "Print - Error" diagnostic were more detailed.