I have owned this machine for about 30 months. I went through a 5 month learning curve before I could constantly make good espresso. For the last 12 months I have used Rustico(Hologram) and Toscano(Big Trouble) 97% of the time. I get two bags on the mail every other Wednesday. I let it rest for 5-7 days and open it. I have become very familiar with these two blends and that's why I have stuck with them. I have two dedicated espresso grinders(Compak K-10 and Super Jolly). I use the K-10 95% of the time since I have to rarely adjust it and when I do it is always a very small adjustment.

For Rustico I use 19.5g of coffee and pull 1.5 to 1.75 ounces of liquid in about 25sec. That is what I have used for the last 12 months. About 6-7 weeks ago I pulled a shot of Rustico that tasted very sour and bitter. Complete sink shot. I have not been able to pull a good shot since. For the first time in 12 months I tried changing the dose in both directions, but the result is the same. For the first few seconds the shot looks as I am familiar with, but all of a sudden the cone gets really big and the shot pours slightly faster than normal. It also blonds faster. I figured for the first time in 12 months I had gotten a bad batch of Rustico. The next week I got two bags of Toscano and I couldn't make a single good shot out of it. At that point I started cursing Counter Culture Coffee thinking they were doing something wrong with their roasts. I ordered 1lb of Black Cat which is another blend that I am very familiar with. The same thing was happening with Black Cat. At that point I figured it had to be my equipment.

This is what I did:

1. Ran Grindz through the K-10. didn't help
2. Disassemble the burrs and thoroughly cleaned them on the K-10. didn't help
3. Tried using the Super Jolly instead. didn't help

At this point I realized it wasn't a grinder problem so it had to be the Rocket.

This is what I did:

1. Backflush session with cafiza. didn't help
2. Decalcified the HX even though it wasn't needed. didn't help
3. Played with lowering and increasing the brew pressure. didn't help
4. Ran some simulated shots with my SCACE and brew temperatures were correct(199-201)
5. Replaced the Motor, shower screen, group gasket, cam lever, brew lever valve, drain valve, mushroom gasket and Gicleur screen. nothing helped

When this problem started I posted in the forum's coffee section. Someone commented that because of the recent changes in weather in Colorado that maybe that was a contributing factor. For the last three weeks the weather is back to normal here. Temperatures and barometric pressure are back to normal so the weather wasn't a contributing factor. During the summer months we get the other side of the spectrum here and I never had a problem making espresso during those months.

Sorry for the very long post, but I wanted to cover everything. Other than performing an exorcism on this machine I don't know what else to do. I would greatly appreciate any help.

switch roasters. test the water. go to a coffee shop order some espresso and then order some beans from the exact batch and pull some shots on your own machine.

Like I mentioned in my post I did try another roaster(Intelligentsia's Black Cat). The result was the same. I am pretty sure the problem is my machine. I just don't know what in the machine is causing the problem.

I have been using Aquafina water religiously for the last 24+ months since it reduces how often I have to descale.

I would point to a problem with distribution. Usually when I get early blonding, there is channeling. It's sometimes in the middle so it's hidden by the cone at first. I would investigate if there were any changed in your technique or morning ritual.

Could your filter basket be worn out?

brianl wrote:I would point to a problem with distribution. Usually when I get early blonding, there is channeling. It's sometimes in the middle so it's hidden by the cone at first. I would investigate if there were any changed in your technique or morning ritual.

I am very precise on my dosing, distribution and tamping. My technique hasn't change in over two years. I dose from the grinder into a cup. I weight the dose on a .1 scale. Stirr the grinds with a whisk. Pour the grinds in the basket. WDT with a dissecting needle. Meticulously level the grinds with the needle. Tamp with an Espro tamper calibrated at 30lbs. The whole process is slow, but effective. It takes me about 2mins.

I upgraded from my Super Jolly to the K10 to get rid of this ritual 2 years ago. The K10 was an improvement as far as forgiveness. My OCD caused me to continue this ritual even with the K10 though. I haven't change my technique. It is not a distribution problem.

caffeinatedjen wrote:Could your filter basket be worn out?

That is one thing I didn't think about. The basket I use 99% of the time is an HQ basket from Espresso Parts. I bought it a few months after I bought the Rocket. I make 3-5 shots daily. It looks new, but once I get home I'll try the factory basket and one of my VST baskets. Fingers crossed.

This sounds strange. Can you publish 5 pictures?
filterholder/coffee after grinding before tamping
filterholder/coffee after tamping
from the shot, at the beginning
from the shot, close to the end
filterholder/coffee directly after the end of the shot

Have you checked you brew pressure? The sudden change in cone size sort of sounds like your OPV is (for some reason) set too high or suffering for some scale blockage.

What about YOU? Have you changed anything in your life, work, extra stress, new health issues you are unaware of? New medications?

The suggestion to go to good coffee shop and sample a known well prepared shot is sound, as this will take your taste perception out of the equation.