The first step when trouble-shooting a laser printer is to try to isolate the problem. Oftentimes, just cleaning the interior and exterior of the printer can be helpful. Do not submerge the printer in water. You may use a damp cloth to gently wipe down the outside of the printer, or better yet, use a cleaner specifically designed for electronics. To clean any dirt and debris from the inside of the printer, spray with a can of condensed air, making sure that there is a clear path for the debris to exit. Use a clean lint free cloth to continue removing the loosened debris if needed. All laser printers generate very high internal temperatures and have the potential to overheat. To avoid this, a thermal fuse is incorporated in these printers to prevent them from overheating. If this fuse is faulty, the printer may get overheated and damaged or the fuse may signal the printer to stop printing even if the printer has not yet overheated. If your laser printer prints dark spots, the ca...