EQ5 Classic, suddenly no more milk foam

It is an EQ5 (TP501) without integrated milk container.

A few days ago we wanted to make a cappucino again, but came out more like a latte macchiato ;-) The milk frother no longer does what it should. I have paid attention to the right milk with 3.3% protein content, also that this comes cold from the refrigerator.

Our machine is top cared for, is cleaned every evening (including brewing unit) and every 4 weeks decalcified and cleaned with original cleaner.

The milk frother works with the vacuum created by steam pressure. With this he pulls the milk through the side hose from the container, heats it with the steam that is generated in the machine and the milk proteins coagulate into stable bubbles. So the theory... If this no longer works, in my opinion, simply too little steam comes out.

I completely disassembled the machine today. The hoses all look like new, except for the one from the brewing unit to the outlet, which has a slightly brownish tinge, but is completely free.

The pump also seems to be working fine. I did not open the pulsation damper and the motor-controlled large valve, otherwise I really disassembled everything, including the outlet manifold. There, in one of the three outlets, sits a small, cone-shaped valve with a lip. Probably the one for steam generation?

Can it be that the instantaneous water heater delivers too little power? By design, the 240V AC should be operated, but I have measured only about 130V AC. The strongest heat is set in the machine setup.

If the coffee is still hot, the problem should not be with the heater, but rather with the outlet distributor....if the seal is defective, the machine draws the wrong air. It is also possible that a nozzle or hole was enlarged inappropriately with some utensils during cleaning.