Thank you Mike, I have removed the tank after learning where the leak was occurring. That appears to be either at the bottom edge of the sensor seal, or possibly, through the brazing at that location. After dismounting the tank, I have cleaned the area thoroughly, by the way, this tank was professionally cleaned during the restoration earlier so its interior is good and there’s no rust. I found that the surface underneath the seals had a couple of spots that were higher. These were clearly part of manufacturing shouldn’t have made much difference, but perhaps they did. I have included a picture of where I am at the
