Clean the outside of the machine using a slightly damp cloth. Do not use the cloth on the inside of the machine.
Open the printer cover and remove the toner cartridge. Using a dry, lint-free cloth, wipe down all interior surfaces.
Download and install the HP Laserjet Cleaning Utility from the HP website (see Resources.) Installation merely requires copying the files onto your hard drive.
Once the files have been copied, open HPPCLEAN.EXE.
Select "Clean" from the main menu. This will bring up the "Print" screen. Select your model of printer
Select the number of cleaning pages to print. The default number is three; extremely dirty printers may require anywhere from six to twenty pages to thoroughly clean them. If you have been cleaning the printer
regularly, three pages should be sufficient. If prints are emerging extremely smudged, with the spaces in letters filled with ink and lines appearing in the margins of the paper, select 10 or more pages. If in doubt, select more cleaning pages -- the printer will not be harmed by excess prints.
Click "OK." The printer will cycle through the cleaning process by printing several different patterns on one or more sheets of paper. The patterns clean the fuser and print head as they are printed. When the process is complete (which may take up to 15 minutes) dispose of the pages in the recycle bin.
Print a test page to ensure that the printer is working satisfactorily again. If prints are still smudged, run the cleaning cycle again.