ECAM 352.57.SB Milk is not pumped/sucked in

Hello,

Recently, the milk foamer in my ECAM 352.57.SB works only sporadically. Sometimes it does not work, then after two days suddenly again, then not again, then after a few minutes again, and currently no longer. This seems to be independent of cooling or quality of the milk.

I always clean as directed, also decalcify as soon as the decalcification prompt comes up. I have also used a replacement hose, without success. I also can not see any systematic when it goes and when not. Jerking the milk container because of any coupling problems also brought nothing.

I have attached a video and linked it as well.

At the bottom of the milk it also bubbles a little, but the milk is not pulled up, with any of the milk preparations. Yesterday it went again three times in a row, this morning not at all.

Any tips on how to fix it would be greatly appreciated, thanks in advance!

Video of the error (YouTube)