Is your Lexmark printer pulling paper through crooked? Is there a smudge of ink on the backside of the paper? My Lexmark Z645 printer prints sheets crooked after about 100 sheets. Here is a way to repair your Lexmark 600 series and possibly other printers.

Open the front cover to access the inkjet cartridges. After the cartridges come to center, slide them back to the right. There is a piece of plastic just below where the cartridges ride. If yours is a light color you should be able to see an ink smudge. Believe it or not, the paper is getting caught on this smudge. Clean this area with a cloth and Isopropyl alcohol. You will see the smudge of ink come off onto your cloth. Allow the area to dry well, usually just a few seconds. Your prints should come out fine now. This may work for other inkjet printers. I hope this works for you.