I am getting verticle black streaks when I print, please help.

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 but NOT the fuser.
If the page is clean the problem is most likely the fuser.
Hope this helps