Milk foam times Yes times No

Hello,
since I am desperate with the Melitta support I need times your swarm knowledge.
I have bought a Melitta Barista TS.
The first has gone back because it had a high frequent coil whining. However, the coffee and milk froth were great.
Now with the new machine there are massive problems with the milk froth. The milk or steam just spurts and sputters out. From 200ml wanted milk foam land evlt 80-100ml in the glass and that is mostly no foam. But that is not always so. Some covers are super especially when the milk carton is full. But that does not always have to be so.
Im getting desperate ☹️.
Melitta writes only clean milk unit.
Carry out descaling.
Perform Easy Cleaning.
After renewed contact, nothing more came.
Nothing changes. Sometimes Tip Top and other times the kitchen is soiled.
Evlt knows jmd of you where the problem is.

Times ALL elements of the milk suction check carefully.
How the admixture of air is solved at Melitta, I do not know.
Probably something is stuck by milk residues, so that no air and / or milk is sucked.
Did that work at the beginning or not?

The machine is less than a week old. Checked everything that is accessible without unscrewing the device. Negative pressure on the hose is also present.