The print job from hell... :(

[Brian]

Hi all,

My wife's PC (running Debian Wheezy) has our Laserjet attached, and I
can access it from my PC (running Ubuntu 16 LTS) as a shared printer.

I printed a PDF yesterday, but now every time we turn the printer on,
it starts printing that same PDF again!

I've looked at the print queue on my PC - it's empty. I've looked at
the print queue on Pat's PC, it's also empty. I've tried switching the
printer off, I've tried cancelling the job on the front panel of the
Laserjet. NONE of these things work. Each time we switch the printer
on, the damned job starts printing again!

Can anybody tell me how/where to nuke it and so make the printer
usable again?

Thanks!

Brian.