In the gears icon, it shows how to clean the cutter. First remove the foot, needle and needle plate. It tells you to press the "link," then press the cutter button. The cutter will slide out into the center of the needle plate hole so you can clean any lint that is caught in the cutter. Press the next "link" and the cutter will slide back into place.
Also, you need to put oil on the hook race and add oil to the reservoir that is just under the needle plate. It takes a special oil that has a higher viscosity. If you take time to clean and oil every project, or every 3 hours of actual sewing time, it should behave better.