Thnx for your input guys.
Regarding the temperature, yes, the machine has "Low", "Medium" and "High" settings, the machine was set to "Medium", I'll try the "High". What are temp values for that setting, I don't know, it isn't stated in the manual.
Regarding the amount of the coffee in the basket, I know how to dose the coffee, I don't go with N grams, I adjust considering some beans are more dense than others.
I personally believe the problem is with temperature, I don't think the machine can keep the water temperature high enough for this kind of beans (I spoke with a local roaster, he said Ethiopian beans often require 2-3 more degrees for proper extraction). I, under no circumstances couldn't proper extract lighter roasted coffee with this machine. Darker roast Brasils/Colombians were ok. So I went the "easy" way and ordered brand new La Pavoni EP (got a good price for a new unit, ~$450)
I believe La Pavoni would be less picky with the beans type and roast level.