There's a lot of ideas being thrown into the ring. Are there any other symptoms you can share to narrow down the possibilities?

If you brew a second shot, just a few seconds after the first, does the problem repeat itself, or does the second one pressurize and start flowing properly in the expected length of time?

Pressino wrote:One possibility, since the QM-67 is an e61 machine, is that the infusion chamber (the cylindrical bit situated below the brew lever) that controls by means of a spring the rate of rise of pre infusion pressure is not working correctly. Could be a faulty spring or bad seals.

Thanks Nick. Are you talking about the highlighted part of the picture attached below?

Hi John,

I think you may be on to something here. So here's what's happening. When I brew my first shot of the day, it issue is prominent. However, I just tried pulling two shots in a row and here's what I observed.

The first shot was slow (first drop took 15 seconds and then rushed to 8.5 bars and got my yield in 35 seconds or so). However, the 2nd shot was interesting. You know how when you pull the lever half way for preinfusion, it makes a faint sound (you can even feel it as we're holding the lever), that sound didn't come when I pulled my first shot but it did when I pulled the 2nd shot. and the first drop was significantly faster (in 5 seconds or so) and the pressure reached 9 bars in roughly 9-10 seconds into the shot. got my yield in 24 seconds. long story short, 2nd shot was better and I could feel and hear the pre-infusion which I couldn't in the first shot.

Also, after the first shot, the bar pressure never returned to zero and stayed around 3-4. When I preinfused for the second shot, the bar pressure actually dropped to 1-2 and then ramped up in good time to 9 bars.

These are the differences I noticed when pulling 2 shots in a row. Does this help?

JRising wrote:There's a lot of ideas being thrown into the ring. Are there any other symptoms you can share to narrow down the possibilities?

If you brew a second shot, just a few seconds after the first, does the problem repeat itself, or does the second one pressurize and start flowing properly in the expected length of time?

Prashanth13485 wrote:Hi John,
These are the differences I noticed when pulling 2 shots in a row. Does this help?

Yes. I'm more convinced that your brew circuit is boiling away its water. Then, when you want to brew it takes several seconds for the circuit to refill before you see it coming out the head. You're going to have to find out where the water escapes.
Brewhead/drain can be found with a spoon behind the cam.

Expansion valve by watching the silicone tubes (after the machine is fully heated and idling).

Or check-valve (you will see it bubbling out the priming valve's tube, perhaps & priming valve will be hot, if it has a priming valve) Or the pump will be hot (and it's not good for these pumps to have hot water flushing through them).

Good luck.

Thanks again John! I am going to have to figure out how to check all these things. I'll report back my findings soon. Good luck to me.. lol Cheers!