Horisontal lines on Samsung colour laser CLX-3175FN

Hi

I get horizontal lines on my prints. Usually only the first one in a series of pages. The same toner pattern is visible (as residue) on the transport belt on the ITB when I open up the printer.

See attached image for example.

I have changed the drum unit and cleaned every part of the printer inside, even the transport belt.

I have also changed the black toner since its usually the colour that is in the lines.


Any idea what the problem can be?