Dick Coers
My neighbor was an old time Ill Bell lineman. In those days, toll lines were above ground everywhere. They were encased in lead and pressurized to keep them dry. He had a listening device that he would use to walk along the line and listen for leaking air. Then climb up and repair. I would suspect that some one makes such a device, or look for an old line man. I loved the guy, like a father. He had stories that just wouldn't stop. He worked in Northern Canada, running line early in WWII up to Alaska. I sure miss him. Found one but it ain't cheap!