Quoted from Stack15:WM is my only spike game - I mean there are only three to choose from. I am pretty sure the problem is with the stern board.
Just to be sure, double-check your shaker motor to ensure that there is NOT a small blue capacitor soldered to it, as pictured below:
Pinball Life originally had this blue capacitor connected to all of their Spike shaker motors, and it ended up taking out everyone's node board. They had to modify all future PBL Spike shaker motors by removing the blue capacitor (or you could just clip it off).
Just thought you could double-check to make sure that they didn't send you a pre-modified shaker by accident.
If yours never had a blue capacitor attached, then yeah, the issue is most likely the Stern node board.