Why is there a vertical line down the page when I’m printing?

Generally speaking, a visible vertical line down your page after printing is an indication that the image drum in the machine may be damaged.

It could also mean that the machine is reaching the end of its life. An idea would be to check the page count of the printer, or run a quick maintenance check to make sure that the machine isn’t simply in need of a clean.

If this doesn’t solve the issue, then you may need to consider a new machine.