Hi, recently took the back cover off my siemens washer dryer WK14D540GB/03 to replace the brushes. Noticed that a tank on the rear was full of black gunk. So i took a look at the spare parts diagram which points to it being the cooling tank. Can someone shed some light on this? Not sure if i have to clean it out, if so how? does look out of place with black water and fluff inside it. I have attached the diagram where the cooler tank is 0511, Thanks