Intermittent connection is common for wires which have broken inside the insulation. Connection could be there sometimes, other times not. Setting up for a good wiggle test would be a valid approach. Such a test consists of finding a way to continuously monitor the continuity of a wire, like the beeper in a std. meter. Then wiggling the wire/bundle from source to destination, to see if the indication varies or drops out anywhere along the line.
Enjoy,
Rich P