Have managed a CUPS printer addition, but the queue is a black hole.

[Erik Christiansen <dvalin@internode.on.net>]

After a fresh update of CUPS, and a fresh "Add Printer", selecting the first
(gutenberg) model option, printing a pdf page from xpdf caused display
of GUI message boxes indicating "printing started" and "printing
completed", but no printer output.

At localhost:631 -> Job Management, "Show all jobs" gives:
▲ ID ▲               Name     User  Size  Pages    State
HP-LaserJet-3050-1   Unknown Withheld 8k Unknown completed at Sat Jun 23
20:42:53 2018

so CUPS processed the job, but the printer stands silently oblivious,
displaying "Ready". So why no printing?

$ lsusb
Bus 001 Device 005: ID 03f0:3217 Hewlett-Packard LaserJet 3050

$ lpstat -t
scheduler is running
system default destination: HP-LaserJet-3050
device for HP-LaserJet-3050: hp:/usb/HP_LaserJet_3050?serial=00CNCKR73450
device for HP-LaserJet-3050-Fax: hpfax:/usb/HP_LaserJet_3050?serial=00CNCKR73450
device for HP_LaserJet_3050: hp:/usb/HP_LaserJet_3050?serial=00CNCKR73450
HP-LaserJet-3050 accepting requests since Sat 23 Jun 2018 20:42:53 AEST
HP-LaserJet-3050-Fax accepting requests since Sat 23 Jun 2018 20:27:56 AEST
HP_LaserJet_3050 accepting requests since Sat 23 Jun 2018 20:40:42 AEST
printer HP-LaserJet-3050 is idle.  enabled since Sat 23 Jun 2018 20:42:53 AEST
        ready to print
printer HP-LaserJet-3050-Fax is idle.  enabled since Sat 23 Jun 2018 20:27:56 AEST
printer HP_LaserJet_3050 is idle.  enabled since Sat 23 Jun 2018 20:40:42 AEST

$ lpq -PHP-LaserJet-3050
HP-LaserJet-3050 is ready
no entries

I'd like to try an "lpc up", but lpc seems not to be there, and I don't
know which package would have it.

Any prodding in the direction of an exit from the maze would be most
welcome.

Erik