Hello, I almost got the same problem. The funny thing is when i print 2 sided, the front page is very clean and the back page is like the preview above but a few tints lighter. Also, my printer has only 24k prints on the counter. I have read that the tranferunit kit should be usefull for 100k prints. I did the maintance like it's presented on the manual but the vertical stipes are still visible, also with some little specs. Can someone please help me out?
If you did everything in the other post and still have a problem I would be inclined to blame the paper than the machine since everything that can be done has been. What you are describing should only happen with non laser printer paper or very cheap low quality paper assuming the printer is not in a high humidity room.