I have owned an Alex Duetto 3 for several years without any problems. Three days ago I started having problems with machine tripping GFCI.

First, 3 days ago the machine tripped GFCI intermittently when I stopped pulling a shot. Then the trips became everytime when I pulled a shot. However, no trips occurred when I ran water thru empty portafilter.

Next GFCI trips occurred consistently when pulling shots and when running water thru an empty portafilter.

This morning machine trip GFCI when on and plugged in.

Any troubleshooting advice is appreciated!

A bit of a wild guess but perhaps there's some current leakage from one of the boiler heating elements to ground. You can try disconnecting the heater element leads and with the machine unplugged, check the resistance to ground between each element lead if you own a digital multimeter and know how to use it. You could also try powering the machine with the heater elements unplugged and see if the breaker trips. If it doesn't, then try plugging it in with just the brew element connected to see if the GFCI tripping.

In fact, have you tried running the machine with the steam boiler power switch OFF?

How old is the GFCI? Some have shorter lives.

Can you plug into another GFCI cct and see if also trips?

Tried plugging in with steam boiler turned off and machine still trips GFCI.

GFCI is 16 years old

GFCI of that vintage should be OK, but all electronics can fail.

If you have a multimeter and know how to use it:

• unplug the machine
• select the MΩ or Auto scale on the multi meter
• measure between the 3rd pin and hot* with machine controls in the on position

Ideally, the meter should indicate O/L, but more than 25,000Ω [25kΩ]. If it's less, there is an internal leakage. It could be as simple as a small leak over time which has accumulated enough salts to create a ground fault.

*

If testing it with the steam boiler off still trips GFCI, test it with both leads disconnected from brew element.
That should make it pretty obvious which element is shorted to ground. Replace the ruptured element.

If neither element proves to be the ground fault, you can test each component with a multi-meter set in the 200k Ohms range, or continue testing with another component disconnected each time, or watch the machine and see when it trips the GFCI... ie. It tried to start the "Fill boiler" cycle, and the GFCI tripped, then you obviously suspect the pump-motor or the boiler-fill solenoid.