ECAM 26.455 Fuse defective / latte / water

Hello, I have like many the same problem that goes with me the fuse in the delonghi defective.
The machine we have quite a few years without problem or defects.

Problem:
After the milk foam preparation (several) is the last time the fuse broke.
Have then quickly found a solution here and replaced the fuse.

Now the machine ran for weeks without problems...yesterday the first time again milk foam prepared and see there fuse defective.

temperature sensor I measured by:
1. Measurement = 72.2kΩ (warm)
2. Measurement = 108.9kΩ (10min cooling)
3. Measurement = 121,6kΩ (20min cooling)

4. Measurement = 71,7kΩ (put finger on sensor)

The thermal paste was dry, I changed it.

I could then brew three lattes and now the second fuse is defective again.

What else can it be ?

You have already described everything in the coffee world. There are the Delonghi experts. You probably won't get any other answers here.