After 16 months my new Quick Mill Alexia started tripping the GFI. Traced the trouble to the heater element and have ordered a new one.
Not having pulled these out of boilers before, I don't know what I supposed to see, but it looks like the machine may have run low on water as the top 1" is discoloured badly.

Is there some trick to make sure I don't run low on boiler water?
I only brew espresso, and never use the steaming functions.

Pondering this problem, I wonder if the 220 volt European heating element is shorter that the lame 120V model. Thus it would stay submerged more of the time.
I'll try to run the hot water wand more often to make sure water stays higher in the boiler, in the future.

A few days later...

Well the new heater plus a spare arrived yesterday and the machine is making espresso again. Yes!
The damaged element measured 1 meg ohm to ground, the brass retainer.
The new one out of the bag measures nothing to ground and about 9 ohms leg to leg.
I'll test it in a few weeks after it's been under water but I think it'll be just no resistance.
I've started to make sure that water comes out of the 'steam wand' before I spend too much time idling the machine. Just make it a habit.

Note: I've also disabled the stick-on cube relay which shuts the heater off when the pump is on (dual PID model). This way I can make 4 double-doubles back to back, rapidly and keep the work crew working and happy. I pre-load 8 baskets and slip them into the bottomless, no-spring portafilter.

The only future mod I'd make is to convert the unit to 220 volts to keep the pump strong during a pull and to minimize the PID from flashing the lights in the house.

D.