DeLonghi ETAM 29.660.SB - Authentic Cappuccino

Afternoon,

my DeLonghi ETAM 29.660 SB Autentica works perfectly.
However, the milk container no longer attracts milk. Instead, only hot steam comes out of the opening sprayed. The milk or other liquids in the milk container are no longer drawn in.

The machine's cleaning program, on the other hand, has no trouble pumping water out of the machine's milk frothing gland. Also, the quick clean of the milk container works (so if I turn the knob on the milk foam container to CLEAN! -> works: Water comes).

Does anyone know what the problem could be?
It's been occurring since I removed the milk container regulator and cleaned the inside of the container with a brush. So I am strongly assuming that the problem is inside the milk container. I've made a little video of the process so you can get a better idea .