That is most consistent with a connection that cuts in and out, possibly as a function of temperature, Most often, this turns out to be an inadequate solder joint, and the easiest test is to simply to heat each joint until the solder flows and wets every part.
If you want to know which joint it was, you can re-solder one joint at a time and test for success in between. Few of us are that curious or patient :^) A careful inspection with a little wire-wiggling might identify good candidates, but in real life that pays off less than half the time. Just sayin'
