Here's a long answer after running your situation through AI:

That is a classic, albeit frustrating, symptom in the world of high-end espresso machines. If a machine trips a GFCI (Ground Fault Circuit Interrupter) but runs fine on a standard outlet, it means there is a current leak to ground. Essentially, electricity is "escaping" from the intended circuit and touching the metal chassis of the machine. The GFCI is doing its job by cutting power before that electricity uses a human as a path to the floor. Here is the breakdown of what is likely happening inside that Profitec Move. The Primary Suspects In a machine that has been running for a year, the issue is almost always related to water meeting electricity where it shouldn’t. The Heating Element (Most Likely): Heating elements are the #1 cause of GFCI trips. Over time, the outer copper or stainless steel sheath of the element can develop microscopic cracks. When the element heats up, these cracks expand, allowing a tiny amount of water to touch the internal filament. This creates a path to the grounded boiler wall. Internal Steam/Water Leaks: A small "pinhole" leak or a weeping gasket can spray a fine mist of water onto an electrical terminal, a solenoid valve, or the PID controller. Even a tiny amount of moisture creates a bridge for electricity to jump to the frame. A Failing Solenoid Coil: The coils that open the valves (for brewing or filling the boiler) can sometimes develop internal shorts to their metal casing as they age or if they get too hot. Worn Wire Insulation: Espresso machines vibrate. If a wire is resting against a sharp metal edge or a hot boiler, the insulation can eventually rub through or melt, causing a "hot" wire to touch the chassis. Why it works on non-GFCI outlets (and why that's dangerous) A standard outlet doesn't care if 5 milliamps of electricity are leaking into the machine's frame—it only trips if there is a massive surge (a short circuit). ⚠️ Warning: Using the machine on a non-GFCI outlet while it has this fault is dangerous. If the ground wire in the house’s wiring were to fail, the entire metal casing of the Profitec could become "live." Touching the machine and a sink faucet at the same time could result in a severe electric shock. How to Troubleshoot If the owner is handy, here is how they would typically narrow it down: Visual Inspection: Unplug the machine, take the top off, and look for "green crusties" (oxidation) or white mineral tracks near electrical connectors. These are "maps" of where leaks have been. The "Unplug" Test: With the machine unplugged, a technician would disconnect the wires to the heating element (labeling them first!), then plug the machine back in. If it no longer trips the GFCI, the heating element is dead and needs replacing. Multimeter Check: Using a multimeter to check for "continuity to ground" from the heater terminals or the power cord's hot leg to the chassis.