I have heard that inserts like that are a test of the manufacturing process.
There is a really big connector under the playfield under the supercharger where all those optos hook up. Your supercharger is most likely disconnected.
The shifter error is common even on a completely working machine. If you tend to only shift the same way each time(up everytime for example), it raises an error until it sees the other switch pushed. Usually just pushing it up and down will resolve the error. If the ball launches when you shift up or down, you may be chasing a non-issue.
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