Siemens Espresso machine TK54001 water lea...

My half a year old machine makes stronger coffee than it should, i.e. about half of the water doesn't come into the cup but runs to the tray inside the machine. Is it a question of descaling more often, or grinding less fine or is something out of place inside the machine. In the beginning the machine was working fine, and this problem appeared recently around the same time the machine notified to run the cleaning program (which I have to do about once a month). However the problem didn't disappear after cleaning the machine.