Using dark oily coffee beans can cause problems.
Beans will not flow smoothly into the grinder. Beans may literally stick to the walls of the bean hopper
Grinder will become clogged. Beans will not grind properly or your grinder will keep on spinning but no beans are being ground, nor is coffee flowing from the grinder into the brew group.
Shower screen on brew group will become clogged.
I worked on many brands of espresso machines and the Jura espresso machines are the most reliable if low mineral water and dry medium roast coffee beans are used. I have customers with Jura machines that have made 30,000 coffees.
In general your machine will need to be overhauled every 4 - 5 years. Over time the brew group can stall and display - "Error 8". The brew group may have fungus due to the moisture and coffee residue. You machine may be leaking water onto your counter. Your espresso may be weak or watery which usually means the grinding burrs may need to be replaced or the grinder is clogged. Jura recommends conical burrs replaced when counter shows 9,000 cups.
I offer Jura repair and refurbishing service to get your machine working like new again. My flat fee service is the best value compared to other Jura repair facilities and I am able to do most repairs in 2 days unless parts need to be ordered. I carry most parts necessary for refurbishing and repairing espresso machines. I provide tech support for all the machines I repair or sell. If you return the machine to Jura it will take 3 weeks before you get your machine and if it is an older Jura machine they will offer you a discount on a new machine rather than repair.
You may be tempted to do Jura repairs yourself. Your time is valuable and many customers have made the problem worst attempting to fix their machine.