Has anyone ever encountered a hard black scale? I am reconditioning a Rancilio s27 and it has a lot of hard black scale inside of it. The pieces are fairly thin, and are about the size of a square centimeter. I don't think it's the element, because it passes the multimeter test.

But I soaked the parts in Dezcal overnight, and it appears to not have affected the scale. One of the parts appears to be clogged up on one end from the scale. Looking at the diagrams it was the pipe the leads to the pressurestat.

I'm hesitating to open the boiler, because I don't want to have to buy a new seal for it.