If the blue/white wire color goes too many places, you can narrow it down by checking the colors on the Ball Release coil. One side (black) won't be interesting, but the other side of the coil should be a distinctive color. Once you know that you have identified the Ball Release coil, you can find it in the game and actuate it by hand (with the power off) and look for a switch that is detecting whether the plunger is pulled in.
.................David Marston