Hi all,

Just wanted to share this as it has now happened twice and it might be relevant to more. So I started to consistently get bitter espresso. Despite relentless efforts (I've descaled, cleaned the machine thoroughly, etc) the taste would not go away. At the end I've started taking the machine apart and when I disassembled the bottom I've realized that the problem was on the connection between the boiler and the pressure stat, more specifically:

- the copper pipe that starts on the boiler button was completely blocked (meaning with the boiler filled there was no water coming out of it).
- there was a lot of scale accumulated on the connector of the pressure stat to the copper pipe.

The way I've cleaned it:
1) I've inserted a wire on the Copper pipe (that was the only way to get it cleaned really).
2) I've filled the pressure stat connector with a white vinegar solution repeatedly and then carefully inserted a q-tip to take out any remnants.

Obviously all of this was the result of scale accumulated over time on very tight pipes, giving a false read in terms of pressure, thus temperature.

After this bitterness is completely out now, I'm getting great quality coffee, hope this helps!

Panos