Lately, it seems that my trusty Silvia is exhibiting uneven extraction. The right hand side seems be extracting and blonding much quicker than the left hand side of the puck. Of course I've tried various distribution and tamping techniques, but nothing seems to work. An LM double basket seems to help the situation a bit, but you can clearly see the uneveness from the Rancilio double basket.

Does this happen to anyone else? Do you people still think it's distribution and tamping issues? Or could there be something wrong with my machine?

Have you pulled and cleaned the shower screen yet? If not, you should do that as well as backflush the machine with cleaner... and inspect the grouphead above the shower screen to ensure all the old coffee bits are gone.

Are you using a bottomless portafilter?

I've done backflushes, I've taken the shower screen apart and cleaned the grouphead as much as I could but the problem still persists. It's like something internally is blocking waterflow to the left side of the screen.

I'm using a bottomless pf. It gets a bit better when I dose more, but I'm guessing that's normal. The thicker the puck, the more forgiving it will be. My normal dose seems to be correct, but something seems awfully wrong. I've had the chance to try my hand at a La Marzocco GB/5 and the same technique I use to dose/tamp extracts fine. I know those machines are more forgiving than my Silvia, but I'm beginning to really think it's the machine. I just don't know how to fix it nor am I able to determine where the root of the problem could be.

jbbank wrote:I know those machines are more forgiving than my Silvia, but I'm beginning to really think it's the machine. I just don't know how to fix it nor am I able to determine where the root of the problem could be.

Have you checked the brew pressure? High pressure will exacerbate Silvia's fussy tendencies.

jbbank wrote:I've done backflushes, I've taken the shower screen apart and cleaned the grouphead as much as I could but the problem still persists. It's like something internally is blocking waterflow to the left side of the screen.

Hmmm, I know AndyS has mentioned his machine favoring the front of the basket a bit, but I am gonna guess that he is splitting hairs there.

Checking brew pressure as Dan mentioned might be a good idea. See Adjusting Silvia OPV for some lnks and discussion.

To make sure it's the "Machine" and not the "Man" try this for the next few pulls - After you build the shot, and before you lock in the portafilter, try turning the basket 180 degrees. See if the problems stays on the right, or if it moves to the left.