Big blue and yellow streaks

[Andre29]

My 2605dn prints, including the test page have huge blue and yellow streaks down the middle, and are unreadable.  Inside, the belt is covered with toner.  I clean the toner off the belt, but it just comes right back when I print.  What is wrong?

[Repairatrooper]

Bad cartridges are the likely cause of this problem and you will need to replace the ones corresponding to the colors you see on the belt. I have seen a few cases with this style engine where the label on the cartridge that tells you the type and color of cartridge comes loose and drags on the belt, smearing the toner, but as you state you have blue and yellow lines, likey the yellow and cyan cartridge are bad. Very common with refilled/3rd party cartridges but can happen with HP. If the toner level on these cartridges is good, you could likely get HP to replace them under their print quality guarantee. If 3rd party toners you will need to chase your vendor .