I've been making espresso for about 5 months using an HX machine. My flushing method and timings got to a place where the espresso was good not always but fairly consistent. Suddenly, this week, I can't pull a good shot; they tend towards sourness, sometimes with bitterness too, sometimes just bitter, sometimes just sour. I've varied flush and rebound times and can't find the sweet spot. What's changed?

Is the maintenance of the machine still the same?
is the weather changing like it is up here?

Hello Eurodolf
--Stefano has much the right of it, weather here is swinging extremes from dry to damp. A couple hours will make a large difference in humidity and the corresponding difference in grind and brew.
--Another time when I had similar problems, they went away when I cleaned my group and dispersion screen. Backflush with cleaner if possible and add a couple rinse flushes.
--Stale grounds in the grinder burrs will cause taste problems. Does your grinder need a cleaning? Have your coffee bean origins been changed, I have occasional poor batches of roasted beans when I roast. I have had some that were less than good from other roasters but maybe only once a year. Minute Rice® or a similar type precooked rice will help clean the burrs. You can use some old beans afterward to get most of the white fines out. The remainder won't affect the taste much before they are gone. Grindz is good also!

Another take, is that anyone will have an occasional bad week or so before getting back on track.
my1¢
-Richard

Hi guys.... thanks for the thoughts. Maintenance is the same, dispersion screen cleaned about a week ago, machine backflushed with cafiza once per week and backflushed with water every day or two. Grinder cleaned with grindz about a month ago. Weather, huh? When it gets colder and damper, how do you all change your grind and brew methods?

It could be a bad batch of beans. I had a batch that went stale really quickly, for some reason. Try getting some new.

Change of season.

Had the same thing down here, not a million miles from you. Everything except the bright ones went stale really quickly.

Now that's it's just raining all the time it's all nice and predictable again.

Erudoph wrote:Hi guys.... thanks for the thoughts. Maintenance is the same, dispersion screen cleaned about a week ago, machine backflushed with cafiza once per week and backflushed with water every day or two. Grinder cleaned with grindz about a month ago. Weather, huh? When it gets colder and damper, how do you all change your grind and brew methods?

You just learn over time. Most of the time it is just a grind adjustment. Over time you learn how the beans are going to react and make a small change. As others point out, it could also be a bad roast. Pick up a pound of freshly roasted coffee from your supplier or get a pound from someone else, just as long as it is fresh. See if things get good again.

Thanks Dave, I'll try a grind adjustment. I have a pretty high confidence level in the beans; I buy them fresh every week from Blue Bottle.

Have you noticed if your shots are pouring faster or slower than normal?

Odds are good it's the coffee. This is a weird time of year for coffees due to harvest cycles. In addition, Blue Bottle is somewhat notorious for periodic significant roast inconsistencies.