thanks for response - I pulled the sending unit...that's how I found the problem originally.....can't really get to the part of the tube with the broken seam (it is right inside the tank at the lower right, where the tube exits...about 3" of bad seam). Had to use small flexible mirror to even see the problem. The vent line, as near as I can tell, is soldered or welded to the tank at both ends. I don't think I can replace the line (but maybe someone has done it??). That is why I am thinking of trying to find a plastic line I can put inside the existing tube, then seal the exit. But I am still hoping someone out there has solved this problem.