Thanks for all your help. A pressure gauge and digital thermometer to measure the outside temp. of the group head, helped me determine that my pressurestat was at fault. It would come up to 0,5 bar but after 10 minutes it would just stop. Temperature never came higher than 66 degrees Celsius.

A new pressurestat is giving me consistent pressure at 0,8 bar and the temperature comes up to around 92 degrees after 20 minutes if I flush the group head a couple of times.

I'm really happy with this. The gauge and thermometer are really helpful. I have totally underestimated in the 3 years I've had this.

Is it normal that the group head takes 20 minutes to heat up needing a few flushes along the way? I'm asking to get a feel for if there is anything else I should replace while I'm at it.

Totally normal. But I would suggest heating it up not by flushing but using the so called "dry pumps". Only lift the lever just under the point where water would come out. Then back down, wait, and back up. Etc.

Saves water, is more gentle and predictable

Good to hear you got your machine back up and running. Oh and I couldn't imagine using the machine without a temperature probe on the grouphead. Would feel like flying blind.

Beilliant. Thanks for the tip. It was like flying blind, which was also why it took some time for me to diagnose that there was a problem, because there were so many variables.