Let's start from the beginning.

I bought the machine on March 2013. I got Eric's thermometer a few days later. From factory the PSTAT deadband was .9-1.1. I also bought a SCACE thermometer within a month of getting the Rocket. For the first six to seven months the machine would idle at 208F after 1hr. I had my flushing technique mastered. For the first shot I would flush for 15secs. During that first flush the temperature would climb up to 210-211 for a second and then it would start to head down. 2 mins later the temperature at the group was still heading down very slow and past 199.8F. At 199.8F I would pull the shot. Eric's thermometer would show 204F. SCACE thermometer would show 199.7F. After pulling that first shot(1.5-1.75oz in 25-30sec) the group temperature would go down to high 195's to low 196's and then it would slowly start to climb. It always took about 3mins to reach 197F(what I need to be able to pull a shot at 200F in the basket). I would pull between 6-8 shots every day using this routine and it always worked.

Forward 6-7 months. I figured it was time for the first descale. I removed the Mushroom and all I could see was a few traces of calcium close to the bottom. I decided to decalcify it anyway. I did both the HX and the boiler following the instructions provided in an article I found from 1st line coffee. It was pretty straight forward.

The very first time I used the machine after the descale the Group temperature after one hour would idle at 202.5. Sometimes it would idle at 203, 204, 205.5. Before the descale it would only take 3mins to recover to 197F at the group. Now it takes 8-9 mins to recover.

Things that I have tried to get rid of the problem:

1. Descaled a second time just incase something got loose in the HX pipes.
2. Removed all the pipes that connect to the boiler and HX and submerged them in descaling solution for hours.
3. Replaced all three valves, springs and mushroom gasket inside the group.
4. Replaced all the gaskets outside the group.
5. Replaced the OPV valve(the whole thing not just the gasket).
6. Replaced the Ulka PUMP and Bleed air valve.
7. Replaced the Safety Valve, Expansion Valve, and Water level Probe
8. Replaced the Solenoid 2-way valve.
9. Replaced the SIRAI PSTAT.
10. Increase the PSTAT pressure to a deadband of 1.1-1.3, but the idle and recovery time stayed the same.
11. Tried using other electrical outlets in the house and tried on another house.

The only thing that I haven't change is the Heating Element. I figured if the PSTAT behavior hasn't change and I get the same steam quality as before then nothing is wrong with the Heating ELEMENT. The machine never returned to pre-descale operation. It still makes great espresso, but for multiple shots now I need to wait 8-9mins instead of 3mins like it used to be.

Any Ideas?

Topics I have found with what appears to be the same problem:

Giotto HX not recovering after shot / coming up to temperature

Low temperature grouphead idle on E61 HX Rocket

https://www.coffeegeek.com/forums/espre ... nes/670628