I'm getting a broken line across the top of the page when i print

I think it depends on what you mean by printing from top to bottom of the page.
If you are describing the print being rotated by 90 degrees so rather than a line of print going across the page from left to right, the print goes up and down the length of the page.
The most common cause of this is that you are printing from a Windows application and you have set the page orientation to LANDSCAPE rather than PORTRAIT.
With in the application you are printing from look for the PAGE SETUP options ensue you select PORTRAIT.
This should rotate the print.

Your printer catridge has been faulty.you can check it from another catridge.

Have you tried swopping the yellow toner cartridge.

This can be any of rthe following depending on the position iof the lines on the page. You need to establishe the position of the lines relative to the top of each page and this determines which of the following component will cause the problem

Dirty or damaged developer roller.
Dirty or damaged charging roller.
Dirty or damaged cleaning roller.
Dirty or damaged developer DSD wheels. These wheels are located on the outer ends of the color toner cartridge and appear as a black bushing.
Dirty or damaged transfer roller.
Dirty or damaged transfer drum.

All of them need inspecting and cleaning

The page size is off. Try readjusting it in your "printing preferences". Otherwise, if it is new, back to the store for a replacement. It really should not do that.

yes you have to catch printer making the line and then as a page is being printed you need to open door to stop paper after green cylinder(drum) as it is entering fuser, then you need to remove paper from printer without pulling through the fuser, if you see the line then rub your finger across line up and down page, if it smears at all then its the cartridge if not then the fuser

This is the test to determine toner or fuser issue.
Print a test page
When you hear the paper feed into the machine open the top to stop the machine
Remove the toner cart.
You should be able to see the page with printing on it. (This is before the page hits the fuser)
If you can see the smudge or marks on the page the problem is most likely the cartridge or cleaning roller but NOT the fuser.
If the page is clean the problem is most likely the fuser.

so, what sort of text is it you are attempting to print? what program is in use?

your toner drum coating eject
change toner drum

Toner issue getting to drum - use gen toner cart.

or Drum blade stuffed (lines are down page fro top to bottom- replace drum assy

Drum has been exposed to light faint or blank across copies repeated 4 times down page - replace drum assy

or upper fuser roller stuffed, down page, smudgy print -  replace fuser

LSU(laser) or boards rarely cause issues