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My Mini Vivaldi II has recently been having an issue with the pump where it will not stay at 9 bar consistently throughout the shot. When I start the pump, the pressure jumps up to 9 then quickly drops to 7. Near the end of the shot, in the last few seconds (20-25s), the pressure jumps between 7 and 9 bar. The pump makes a pulsing noise as this is happening. I called chris's coffee, and they suggested that I adjust the expansion valve, after verifying that the pump does reach 10 bar using a backflush disk. How do I adjust the expansion valve? Will this correct the issue or could it be something else? I tried searching for instructions on how to do it but was only able to find info about the vivaldi, not sure if it's the same.

Thanks!

Have you looked at paragraph 8.1 of the User's Manual?

s1v2/MiniV2Manual/Mini_V2_Owners_Manual_RevF.pdf

I checked that and noticed that there is a kink in the tube leading to the expansion valve, could that be causing an issue?

That could do it.