When I bought my B36(2002) second hand in 2010, part of the deal was that the cool box had a new cooling unit. This consisted of a new cooling plate within the cool box, the connecting pipework and a new refrigeration compressor which was located under the port side settee. It worked fairly well, but one of the pipes chafed against the edge of a hole cut through the plywood and eventually leaked all the gas out in 2015. The refrigeration equipment was removed and taken to a refrigeration engineer who found the leak, soldered it up and refilled the system with the required refrigerant gas. I refitted the whole assembly, and it has worked reasonably well ever since. As for the hole through the plywood settee base, well that was plugged around the pipe with rubber foam to prevent the pipe from chafing. Also I’ve fitted some self adhesive half inch thick closed cell polyurethane foam to the inside of the cool box which helps to keep it cool, though while that remains a work in progress, the coolbox keeps the contents cool enough for me, but still runs a bit too often.