When I print, there is one black line on the right side of the page. Little colored dots also appear on the far right of the page. The lines and dots still appear on the gradation and 20% toner tests. I have cleaned out the printer for any loose toner.
If the line and the colored dots also appear on the back of the page, the problem is most likely related to a failing roller in the fusing unit. If the lines and colored spots appear only on the front of the page, the problem is most likely a failing drum unit. You can remove the drum unit and look at the drum itself to determine if the problem is with the drum unit.
When diagnosing print quality issues, pictures speak a thousand words.
If you can, please scan some of your defective images and post them with your reply.
You'll need a website on the internet to host the pictures from. If you don't have one, www.Flickr.com is one that works great, among others.
obtw...... max width allowed in this forum is 460 pixels.