Hook mod issues?

I’m making an animation of a megger test, and I need to animate alligator clips attaching to a figure of some wires, with cables attached to the clips at one end and the megger at the other that follow the clips around during the animation. I followed this tutorial and thought I got the cables working properly. It turns out, after I animate the clips moving from one point to another for the first time, if I try to move the clips again, the cables stop following them. Does anyone have a solution for this?