Coffee leak!

There are several o-rings in the brew unit that could be the source of leaks. I replaced all of those and that didn't fix the problem. After figuring out how to observe the brew unit during operation, I found that the leak was coming from the SBS valve.

The leak is coming from somewhere in the brew unit, but with the door closed, you can't see it in operation to identify the specific leak location.

Use a magnet to bypass the door open detector so you can observe the brew unit in operation. (See video - Saeco Talea Giro brew unit leak diagnosis)

I used a bag clip with an attached magnet and clipped it onto the sensor.

Run the brew cycle. You can use the coffee bypass cycle because you don't need to waste your good beans for this test. And, it's easier to clean up if it's just water.

Look for leaks!

On my machine, the SBS valve on the upper left of the brew unit was leaking during the brewing process. This valve admits the pressurized water into the brew unit and includes a one-way check valve to keep the pressure in.