When the pump and heating element are both running simultaneously, the pressure drops on the pump to around 7 bars. This went away when I moved into a new place but it happens from time to time. I think my next step is to check if there are any other appliances running while this problem happens.

Does anyone else have problems with a small circuit? I'm looking to sell my Anita but don't want to sell something that might have a faulty pump. Thanks

Was happening to me so I am now getting power from another circuit and the problem disappeared.

Code in some areas is that the upper and lower plugs in an outlet are are different circuits in the kitchen. See if that makes a difference.

I have several unused 20a circuit breakers in the box from when we had separate electric heaters in each room, and I'm cannibalizing one of those for a dedicated 20a espresso circuit in the kitchen. If you own your home, and depending on your house layout, it shouldn't be too expensive to run a new line if it continues to be a problem.

A cheap & cheerful VOM plugged into the other socket will tell the story. If the voltage at the plug remains more or less constant [~2v] when the heater kicks in, then there's more than likely an internal wiring problem : Corroded / Loose Connector(s)

7 Function Digital Multimeter at Harbor Freight for $5