This looks to be an accumulation of coffee grounds, oils and simply staining. To keep your coffee maker functioning properly, periodically remove oil, stains, and any sediment from the inside of the coffee maker. To clean, add water up to the 12 mark. Then prepare the coffee maker as you would for making a full pot of coffee, expect add 3 tablespoons of dry automatic dishwashing detergent to the basket in place of the coffee and do not use a disposable filter. Once the signal light illuminates, allow the coffee maker to remain plugged in for 15 to 20 minutes. Unplug the coffee maker, pour out the cleaning solution and then rinse the inside of the coffee maker and the parts with running water. Fill the coffee maker with fresh water up to the 12 mark and perk again. Pour out the water and thoroughly rinse the inside of the coffee maker and the parts. Depending on the severity of the staining, it may be necessary to repeat this cleaning procedure. Please reach out to our Customer Service Team if this does not resolve this issue. Call 1-800-877-0441. We are available weekdays, 8-4 CT.