Morning,

Over the weekend, I took off my dispersion screen to clean it. Sure as nuts, after a few weeks, it was a little dirty. I undid the nut, out came the spring-with-ball-on-the-end (grouphead valve, I believe).
I presume this seals the boiler until the pump is switched on, the spring is compressed, and out comes the water down the channel and through the nut (it has holes perpendicular to its shaft).

Upon reassembly, the pump is now much quieter, and the flow through the group is reduced. I backed off the nut and it remedied things somewhat, but still there is very little pressure now, and the pump doesn't make such a rattle while pre-infusing/pressurising.

Anyone around Montreal with a portafilter pressure gauge I could pinch?

How and how often have you been descaling your Mokita?

It is most likely a bit of scale that has dislodged and is clogging up your brew valve and reducing your pressure. Try this very high tech approach: open up a paperclip and see if you can ream out any gunk that has accumulated behind the brew valve. It's worth a try.

If that doesn't help, you can test your pump, but try the paperclip bit first...

Thanks for that, but I have only recently taken delivery of the machine, just after New Year.
It's exceptionally unlikely that I will have scaled the boiler in two weeks, no?

The steam wand triggers the pump when it's in water-mode and the water emerges with fearsome pressure (from the steam wand).

For amusement's sake, I checked the voltage at the socket, 120V, so it's not underpowered.
Also, the bolt seems to bend the shower screen up if compressed too much and the water drains out of the middle versus even dispersion. Perhaps I should search for a very thin dispersion-aiding washer to go under there.

I cannot believe that the issue is the spring, as the pump should be capable of >100PSI
Also, on the nut, the holes sit proud of the bottom of the group, so the bolt is not in too far as to obscure the holes. I'll have a proper gander later on and get back to you.

Perhaps it's something much more mundane, like overdosing with some new coffee. I'll dig out my backup pack of 49th Epic and see what transpires. I'm getting a portafilter sneeze on unlock, though, so there is pressure, just unsure of how much!

Good luck.

Back to its normal self. That was odd. Perhaps I'll snag a pressure gauge tomorrow and see what's afoot, just for quantitive measurements.

On that note : this machine is not fitted with a 3-way valve. Is it worth to retrofit such a thing? Right now I have no idea how much pressure it's producing...and certainly no way to control it

Happened again, today. This morning, after three days of faultless pulls with home roasted sidamo. It appears to only happen after I reassemble the group head...

Upon unlocking the portafilter, enormous sneeze. Pressure is no worries. Is it possible that the same grind and dose over a few days can now choke up the machine?! Too much expansion of the grind bed? Except that it pours fine for five or so seconds, then begins just dripping. Will loosen up the grind.