thanks for your responses.
I installed a new GFCI, and it was still tripping.
I then tried again to plug it into the other plug I tried before, and I
realized it actually wasn't a GFCI (I couldn't see it as it was behind
a 2 -> 6 plug adaptor :-( Being in the kitchen, I just assumed it was
GFCI, but it wasn't).
So now I know my espresso machine is at fault.
I opened the expresso machine, tied all connectors I could find, tried
it again, and it made the GFCI tripped.
Next thing I tried: changed the cord. I had one at home, so simple
enough. One thing I wasn't sure about is that it had blue, brown and
yellow-green cables (the espresso is made in Italy), but the cord I had
was the typical black, white and ground.
I connected in: black/brown, white/blue and yellow-green/ground (found
that info on the internet)
When plugged in, it doesnt' trip anymore. However, if I activate the
pump, it trips again.
Any idea before I take it to repair. I probably should do that, but I
bought it used on ebay, not exactly for cheap, and sent it to repair
about 5 months ago (they cleaned everything), so my 10 years old
machine already cost me more than a new one :-(
I would hate to fork another $100 on it...
thanks in advance. Fred