I didn't think that this question was on topic under Super User. I didn't flag it because printers are sort-of computer related, but... if it's only hardware?
I'm inclined to say this is on topic.
Printers (with some exceptions) can only function correctly when attached to (or driven over a network by, etc, etc) a computer, and that should mean that printers are generally acceptable.
And while this specific question is most probably related wholly to the maintenance/repair of the printer, there is still a small chance that the problem is being caused by the driving computer.
But this is a bit borderline, so would be interested in seeing what everyone else thinks.
I would say it is on topic.
This question, and its just about the mouse... I happen to think that computer hardware includes "accessories" that help a computer fulfill a function.
In addition to printers, there have been questions about KVM switches, monitors, mice joysticks, and loads of other other pieces of hardware that is not directly considered part of a standard computer. Across the board, these types to question seem to be open.
So for consistency, and because there is not reason to change it (I don't see it as a stretch to call it computer hardware), it's on topic.