After the motor has run for awhile I see evidence of oil in the area around the pushrod tubes. I don't think it's the valve cover gasket. Is it common for these engines to leak at the tubes? I see in the Moss diagram that they say to "swage the tube ends and seal with Blue Locktite". I wonder if the last person who did head work forgot to do this. Someone educate me on "swaging" and I assume this is done when the head is off and being reassembled? Is there a sealer that can fix this properly without pulling the head?