I have talked to a couple of people from Germany and they said the water in Germany is very hard. You probably have a mineral build up in your steam system. Do you have one of the old boilers or is yours one of the new brass boilers? If you have one of the new brass boilers you can use Durgol to remove the mineral build up, but you should remove anything that is stainless before you do. You can use one of the citric acid based cleaners designed for espresso machines also. Mix the solution in the water tank and pump it through the steam wand or brew head, then turn off the machine. Don't let the boiler heat with the solution as it can cause damage to the silicone gasket. Remove the water tank and drip trays and lay the machine on the steam wand side to allow the solution to get to the steam valve. After 10 minutes right the machine. Replace the water tank and repeat the first process until the steam wand opens. Then just pump water through the steam wand. If your water is that bad you need to decalcify more often.