Dell 2330D/DN, 2350D/DN Streaked horizontal lines appear on the page., Streaked vertical lines appear on the page.

The printhead lens is dirty.
The toner cartridge is defective.
The fuser2 is defective.
Try the following:
Clean the printhead lens.
Replace the toner cartridge.
Replace the fuser2.
Streaked horizontal lines appear on the page.
The toner cartridge may be defective, empty, or worn.
The fuser2 may be worn or defective.
Try the following:
Replace the toner cartridge.
Replace the fuser2.
Streaked vertical lines appear on the page.
Toner is smeared before fusing to the paper.
The toner cartridge is defective.