Did you figure out your issue? I am having a very similar issue with White Water. The upper portion of the GI is out (brown and white brown wires). I replaced the fuse, and strangely, it worked for a couple games, but then just stopped in mid game. Checked the fuse with multimeter and it has continuity. I am a noob, and when I try to follow the pinwiki steps, I get confused:

How do I use the multimeter on connectors? In other words - I don't see how you can get the probe good contact on a wire when the connector is seated on the pins (step 4 in the pinwiki directions). Should I stick the probe down into the female portion of the connector to check voltage while the connector is off the pins?

Should I take out the power driver board and inspect the soldering? Being new to pinball, I have never taken a board out. It seems relatively simple to get out (just label then remove connectors and loosen screws?). Or should I call a tech?

Would love to know if/how the OP solved his issue because sounds almost identical to mine. Thanks for any help!