The Grinding Burrs are worn down and need to be replaced. (Usually need to be replaced between 3,000-6,000 cups).
Clean the grinder. Coffee bean residue can accumulate quickly, decreasing the effectiveness of the Grinder.
Oily Espresso Beans will seriously decrease the effectiveness of the Grinder; however, this does not mean you shouldn't use them. Adjust the grind setting to a coarser grind (The first setting being the FINEST grind). Furthermore, using oily beans requires a dedication to maintenance. The Grinder and Brew Group need to be cleaned regularly to prevent major malfunctions. The components of a dirty machine work much harder than those of a clean machine. Overall, try to limit the use of oily espresso beans.
