Why is my laser printer printing blurry on the sides? -

I have an HP laserjet 1020 black and white printer that I have had for about a year. Just recently when it prints, both side margins are printing heavy and blurry. I thought the toner may be running low, but a new hp toner cartridge did not help. Any ideas?

The heads are probably dirty, you can clean them yourself with rubbing alcohol and a cloth that won t leave any fuzzies, but I strongly suggest taking it to a printer repair shop for a proper thorough cleaning