hmm, the lid is still the issue. The cold lid meets the warm air/squab and creates
condensation. The lid is not sufficiently insulated, new, old, or indifferent. Are you sure you used a proper closed cell
polyurethane foam at least 75mm thick? No air gaps. Anywhere.
Try this, at night, put a lamp in the cabinet, try to make the
cabin as dark as possible. If you can see any light at all around the lid seals, they aren't sealing properly....
Good luck!