I recently contacted a local Pinball Guy here in Omaha (ironically called The Pinball Guy who services much of Nebraska and Iowa) regarding my DE Simpsons (Audio Hum, Bad Switches, ROM Questions). He said that Data East put the wrong Schematics in their Manuals Intentionally so operators wouldn't be able to figure out how to fix things (presumably leading to more direct support from them)
He had worked on our local company's POTA and the Sound Board was 100% Wrong compared to the Manual itself
On one hand it's deceptive business practices to do something like that, on the other hand I now understand why they didn't last long under the DE Name
In summary, I'm using some Pinside Threads for a Workaround on the Hum (During Attract Mode & Diagnostics Mostly) and basic trial and error on the other issues. Anyone have any further feedback on the advice I got or the issues themselves?