Hi, i think my brewing pressure gauge needs calibrated or replaced on my Vibiemme Super, no matter what i do, it's never on 0 bar,
lowest i've seen it is 4 bar, and during brewing it's about on 9, which could be too low since it's not on 0 to start with, is there a way to adjust it, or does the gauge need replaced, please let me know, thanks,

Just to make absolutely sure...is this a plumbed-in model? If so, that's your line pressure. If not, I don't know what to tell you

Just taking a stab at the obvious...

Yup, its plumbed with rotary pump

4 bar (~60psi) seems a bit high for line pressure. Does the manual state the recommended/max pressure?

30 psi is recommended for my Brasilia Firenze. I installed a pressure regulator in line with my Chris Coffee water softener/filter kit and have it dialed in at a steady 30 psi.

I just read here that anything over 4 bar is too high, i never figured that brew pressure is related to line pressure, thanks for mentioning that!

Most vendor's spec no more than 4 bar of mains pressure. I run my machine at 3 bar and as noted, input pressure effects brew pressure. Raise your line pressure and your brew pressure goes up, lower it and it drops. It makes adjusting a machine with an onboard rotary a pain since you have to pull the case off to adjust the pump. However, once it is set, you will probably not change it again, unless your municipality changes their supply pressure. Get yourself a regulator and pressure gauge for that regulator and install it just before the supply line to the machine.