I will warm up the subject. I have a practically exactly the same problem with the twin model 1200. The espresso machine is 2.5 months old and has stopped practically frothing milk. The coffee maker made about 10 coffees a week. I carried out the descaling process 2x without any results. Frother cleaned after each use. @ markap75 Have you dealt with this problem at home or is it still possible to return the device for warranty?
I sent it back to the service 2x. It turned out that even despite cleaning, they did not. In this metal element that is removable (this part of the frother, such a tube) - there is such a small hole, very small, the tip of the needle is located there. Mine was just stuffed / stuck or something and didn't take in air for foaming. Just push it. I do so from time to time and it works [/ u]
@ markap75 indeed the problem was a clogged hole I spent half a day cleaning and descaling the machine and the problem is so trivial that it is eliminated in five seconds without any disassembly of the machine. It is a pity that the instructions did not write to periodically clean this hole.