For some reason if people have a leaky Bacchi they first thing they suspect is the o-ring seals are needing replacement

In our experience this is seldom the case, it usually means you have one of the first or second generation bases (part 28), which was prone to warping as it was cast aluminium

After much discussion we are now able to confirm that part 28 is now machined from extruded aluminium, or bar stock if you are American.

Confusingly the manufacturer has elected to then coat the base, possibly anodising, with a stipple finish that makes it look like the part is still a sand casting.

It is not the way I would choose to reassure customers that the part is now made from an extrusion, but there you go.  I can confirm that it is a coating though as it can be driven off with a screwdriver at the edges if you are determined

Anyway, the first thing to do if your Bacchi plays up is to lubricate it.  If you don't want to go to the hassle of obtaining Molykote you can use some humble olive oil

It the majority of cases this will resolve the issue.  If not, order an extruded base, part 28.  Don't waste your time just buying new o-rings. We have never replaced ours and it has had years of use.  It has had a new base though :)