For any print quality issue the first check should be the toner cartridge, especially if the cartridge is compatible or refurbished in a Lexmark printer. Any cartridge other than a brand name Lexmark OEM or Lexmark re-manufactured cartridge is suspect number one, even for some jamming problems.
Be on the look out
When you open the bag the cartridge is shipped in, watch for excess toner in the bottom of the bag and on the cartridge. If you find loose toner in either of these places put the cartridge back in the bag and locate another because, if you use it in that condition it’s going to leak toner inside your printer. The toner will pile up on the inside causing smudges and streaks, pages folded at one or both leading corners, and eventually jamming at the entrance to the fuser. Not to mention the print quality issues you’ll experience.
Here’s what happens
Under the cartridge, the toner will coat the Transfer Roller and show up as grey on the back of prints, and/or inefficient image transfer to the paper from the image drum in the cartridge.