Similar problem was found on 74 360CB caused by corrosion at the spark plug end of the coil wire (both sides). The Coil is molded to the spark plug wire, but the spark plug connector seems to be just screwed into the end of the wire. When un-screwed, the connection had a green tint = corrosion. Once the corrosion problem started, I´ve had to re-terminate the spark plug connection to the coil wire every couple years. (So I´m probably not making this connection properly.) Tom