Hi asqui,Originally Posted by asqui link=1141602837/0#0 date=1141602837
First things first.... you need to give the machine a good clean out.... back-flush all three Groups with Espresso Clean or similar and then flush out til all signs of the Espresso Clean are gone. Then, you need to remove the baskets from each PF, and probably the spouts too and get stuck into these with some dish-washing detergent and one of those stiff bristle dish/pot scrubbers. The spout covers will need to be removed so that you can get stuck into these with DW Liquid and a toothbrush or similar.
Once all have been cleaned and thoroughly rinsed with fresh, clean water then you can re-assemble and try your hand at pulling some more shots.
Sour shots could indicate that the brew water temperature is too low. Bitter shots, such as you describe, could point towards over-extraction because of...
a) Insufficient dose,
b) Grind setting too coarse resulting in too short a shot time,
c) Uneven extraction through coffee cake..... i.e. channelling
d) Improperly tamped or uneven tamp.
This all supposes that you are now testing with clean PFs and Groups :)
No doubt some of our Pros will be able to provide you with more help than this and measures you can use to overcome them, but these are the first things that come to mind. Sounds like youre doing pretty well though for the majority of the time, especially with a strange machine. Id like to be able to do half as good as you in the time youve had available asqui ;D.