... mine leaks, there is water on the table and inside the base -- it even blew 30mA fuse
My guess without knowing more is that you may have a poor seal at the top of the piston cylinder (inside the stainless piston body).
This piston body forms the lid to the cylinder, and there is a single o-ring responsible for maintaining the seal. If the seal is failing, you will get water escaping through the back of the stainless piston/group body, where it falls in behind the side walls covering the boiler into a small plastic tray around the edge of the base of the boiler.
To see if this is where the water is coming from, release the three sidewall pieces by removing the boiler cap and the two screws holding the hard black cover on the top of the boiler (catch the sidewall pieces carefully, or they'll all fall at once). Watch the rear bottom of the group where it meets the boiler, there is a small drainage hole here.
If this seal is a problem, it is a simple fix to replace it once you have the right part. Possibly some additional food-grade grease/sealant might help (perhaps even a bit of vaseline, according to the helpful folks at Espressotec).
This drainage design handles small amounts of water well - boiling it away - but a bigger seal problem can cause larger amounts of water to leak during lever activation or even direct drainage from the reservoir ... both of which will flood this small tray, overflowing and pouring onto the counter, and possibly into the base. If this happens, you are at risk of shorting out the thermal reset fuse since it sits flush at counter level and is exposed.
Getting at the seal is very simple -- the Achille is extremely easy to disassemble. Once you have removed the sidewalls, disengage the bolt/screw locking the lever arm to the piston. Also remove the 3mm screw that joins the upper piston body to the lower group body (at the front of the group). Next, loosen the two hex nuts fastening the upper steel body to the boiler. Gently lift the upper body up and away from the machine, which exposes the black plastic cylinder and piston, along with the o-ring that seals this cylinder to the piece that you just removed. Be careful when putting this back together, in order to avoid pinching the o-ring.
Just wanted to add a note about the \"pull.\"
In the 60s I worked at a Cafe in Evaston, IL. We had a four pull machine and the key to a good cup was to \"pull\" the lever down almost halfway, then return it to the top and then pull down steadily.
I pulled many shots this way on the Achille, and it was about the only way to get close to double volume. Shots were very well-rounded - better, clearer taste profile - if not as heavy in body or as buttery as a pump-based espresso. A single pull nets 1.5oz with no coffee present, so a pull-and-a-half helps to keep 1.5oz in the cup despite the thirsty coffee puck.
I actually found that the best-bodied shots were from pulling a ristretto with a single uninterrupted pull. There was, of course, a preinfusion stage ... I just didn't reverse the lever or release pressure. Took a hang of a pull, but the results were worth it. Shot volume on these was, well, rather tight. Think about how much fits in the bottom 1/3 of a 2oz bodum pavina glass.
FWIW: I also used a bit more coffee, at a coarser grind, in the Achille than the Gaggia Espresso, though they both use the same basket/portafilter/group. The Achille is both more forgiving of and more dependent on a high dose.