HP Laser printer issue with marks on the printout

[wayneleonard]

I have an issue with a HP Laser printer and i am not sure what bit i need to look at cleaning or replacing

I print out a page and i get faint coloured lines down the page, so aprox an inch from the top of the page i have a blue line around 3/4 inch wide across the entire page and a little bit of yellow under that, then a couple of inch further down i have a red one, and then same again further down to a yellow one

I have tried to take a photo to show the problem, i am printing on waterslide decal paper which is why the paper is blue, and i am printing with a white toner cartridge in the black ink slot so those squares on the page should be white (and are being covered over with some coloured ink)

Thanks