Desperate--two group heads, only one produces good shots

[coffeecottage]

I have a 2 group Iberital Espresso machine. One group head produces excellent shots. The other group head produces shots that are much darker and muddier looking, the stream seems thicker & frothier, and the pucks are consistently soupy. These shots are bitter tasting.

Here's what I've done to try and remedy the situation. I've replaced the dispersion screen, solenoid valve, and I have also adjusted pump pressure. I have a water filter and softener on the machine, so I don't think it's the water...I don't know what else to do. Everyone I talk to seems at a loss. I don't think it's user error because I try to do everything in my power to produce a good shot on that side and it always comes out the same. I get beautiful shots with firm pucks on the other side...so I know I'm dosing the basket correctly and tamping fairly accurately.

Help...anyone? Thanks for reading.

 

[Alun_evans]

Essentially each group has a heat exchanger that runs through the boiler, providing water to that particular group. Wet pucks can normally be traced back to one of two or three factors- but if the other group is producing good shots would think it is a temperature issue. I would check the exchanger for calcification - buildup inside the HX'er. Calcification could mean that the water temperature in the exchanger for that group is 2-5 degrees cooler than it should be- thus the nwet puck and "soupy" shots. You would need to empty the boiler and open the pressure plate off the side of the boiler to check, could be a big job. The alternative would be to check the pressure of the boiler and notch it up a few turns. Pushing the pressure up to 1.35+/- might also help.

 

[coffeecottage]

Thank you thank you thank you...I will try this.