Neff S52M69X1GB/16 dishwasher leaking

Has anyone solved a leaking cabinet on a Neff dishwasher? It appears to be leaking from, or near to, the vent at the lower rear left hand side of the tub. I have replaced the ‘Vent Cover’ and its associated gasket, and in desperation the complete ‘heat exchanger/fill device’, on the outside of the machine. It is a steady (Almost running) leak, only when the machine is working. Impossible to see between the heat exchanger and the cabinet to identify the source. Have removed a lot of sound deadening around the vent to try to find the leak without success. I can’t find any pin holes in the stainless steel cavity. Any pointers or leak tracing tips welcomed