Once the rudder was off the boat we were able to inspect the tube. There was a "hole" in the top of the tube below the packing gland near the bottom end of the tube. The bottom of the packing gland fitting was clearly visible. They had used some kind of putty or sealant that was blue in color and had become soft and degraded over the years and was falling out in little chunks. The area was picked clean of marine growth, shell remnants, dried algae, etc. and sanded as best we could given the tight location. The old compound was picked out so new material could be added. West system epoxy was used with a 50/50 mix of colloidal silica and graphite powder and was pressed into the void to fill the hole and renew the flange seal. A wooded dowel that was the same diameter as the rudder stock was coated with a mold release agent and pushed up in place of the rudder stock.