All other issues aside for a second, the condition of your machine is thoroughly jaw dropping.

If you wet a few layers of napkin or paper towel you can create a seal that proves what we see. The seals are installed correctly and they are not damaged. At this point, though I don't feel it is necessary. I feel the machine is not the issue.

I am not familiar with your grinder, so I can't speak to it.

The shot in your cup doesn't look tasty.

[Edit: after thinking about this a bit, I would look at the grinder and beans. As others have said, the grinder has to be able to do a choke shot. But this is probably a completely untouched grinder, that sat as unused as the MCAL. So the why it can't do a choke shot adds to to the mystery of this scenario. A light tamp is all that is necessary when the grind is fine enough.

If I lived in Vancouver I'd bring over the Niche with my beans and we'd have this figured out in no time. ]

Trying 15 roasters, let's say $16 a bag of 12 oz coffee,

= $240 of 5100g of coffee....you sure you pulled that many shots?

Sounds to me like a grinder issue. When I had my MCAL my first 3 shots were all choking cause I would grind so fine for my pressure profiling machine.

Yes its been expensive! I have a Jura too, so the beans aren't being wasted.

But that doesn't change the fact that I cannot choke it.
I got the local shop to grind to finest grind and I have same issue.
Lever goes up, minimal resistance.

Interesting thread! I know everyone keeps saying grind finer, grind finer, but it seems like you should be grinding fine enough if it's icing sugar, and you've had a local shop grind as fine as they can.

For me, the next step would be to get one of the rubber backlushing discs and cut it to the size of the basket and see if that chokes the machine. My hunch is it won't and then you can figure out where the water/pressure is going. If it does choke the machine, then it's your grind. The only major flaw in this is that if it does choke it, you have to be very careful getting the portafilter off (machine cooled all the way down, don't let the lever spring back up by itself or hit you)

Without sealing off a portafilter, one way or another, and pulling the lever to do a pressure test, the seals aren't proven to be doing their job.

Until that's done I wouldn't waste any more coffee.

Also, wrapping a wet dish towel around the portafilter and going slow is how I've heard one should deal with a choke shot.

Ok so I took apart the group and replaced the gasket between the grouphead and the boiler.
That seems to have fixed it!
I don't really understand why as I couldn't find any leaks..
Anyway, I can now choke the machine, almost too easily.

So... now I think I have the opposite problem -- I think my spring is probably tired..
I've ordered a replacement spring from Stefanos.. Would adding a booster spring be good idea?

Does anyone have one they can sell me or give me advice where to find one?
Thanks!

Ok good to know!
Did you get your new spring from Stefanos?
Thanks!
Mike

Awesome thanks!

I'll make a jig like you did.
Can you please give some hints on removing the lever pins?
I worry that with a jig on it will be hard to pull them out as they will be 'covered' by the wood of the jig.
Do you move the lever handle down as the spring compresses?
Thanks!
Mike