The Karcher foam maker does not foam - the foam maker does not provide foam

Hello.
Recently, a pianist like me from a photo got stupid

Used together with the Karcher K3 washer - which works normally.
The problem is that it started to produce very low foam. Two streams fly from the nozzle. One very weak straight ahead and some foam flies into the car, the other straight down like a tap with a leaky strainer, and water gets into the container itself. Probably something had to break inside, because until now I used the active foam from Tenzi and it was ok, and once I poured a very strong acid into it into the rims. After this activity, when I flooded the normal foam, she became stupid. Is anyone able to help me?

The foam maker gets too much pressure. Take apart the tip of the foam which is coming out and pull out the center with the strainer and open (enlarge) this tube from inside.