I've learned over the years to not depend on the in-truck analog tests as they only "sample" the voltages and I've seen many a tech that took these readings as gospel and got bit. Also, when I do an ohm test on an overmast cable I disconnect both ends, attach negative lead to say the red wire at one end and positive at the other. strum the cable like a guitar string at the point you think the problem is (this duplicates the bouncing around of the cable during lifting/lowering). If you have good continuity, disconnect negative lead and connect to another wire, leaving the positive on the red and repeat the strumming. Repeat this procedure through all the wires of the cable to verify that you aren't getting a short between wires that could cause your problem. I've had a truck lose wire guidance when lowering and honking the horn at the same time due to this.