The idol was a little intermittent on my Indiana Jones, and eventually stopped working. I swapped all sorts of components around between working machines with no luck. So i went back to the trusty manual and looked at the wiring diagram. As i was noticing how the idol motor was driven from the 8 drive PCB (an additional board to IJ, Star Trek and Twilight Zone), i wondered if any of the other components driven from that board worked.
Most of the others driven from these transistors are flashers, and none of them worked!! At least i narrowed down the problem now (after spending hours swapping all sorts of other boards and motors!). I then unplugged and replugged (also known as reseating) each connector going to this board. One by one, restarting the machine to see if the issue disappeared. Finally, i narrowed it down to the Z connector between J114 of the power driver board and J210 of the MPU. After lightly sanding this connector with some emery paper, the issue has not since reappeared.