Quoted from amxman:
How do you know by looking at the schematic that those are switches 1, 2, 3?
It’s a matter of deduction.
(1) The label on the Litebox Advance Unit says the inside switch (first switch) is the “Reset Completed” switch. If it’s reset, that means the unit is at the “zero position”, which is how it is labelled in the “Subtract ‘Ball Count’ Unit” circuit on the schematic.
(2) The same label also says “Comp. CIR. To Subtract ‘Ball Count’ Unit Coil” for the second switch. Correspondingly, you can see a closed make-break switch in the “Subtract ‘Ball Count’ Unit” circuit on the schematic.
(3) The same label also says “Open CIR. To Subtract Coil” for third switch. Because the label is on the Litebox Advance Unit, it is referring to its own subtraction coil. Correspondingly, you can see an open make-break switch in the “Subtract ‘Litebox Advance’ Unit” circuit on the schematic.
Lastly, the switch state as they appear on the schematic—normally closed or normally open—reflect the game when it is fully reset, ready to play, and with the power cord disconnected. Bear that in mind when you see closed (NC) or open (NO) switch symbols in a circuit on a schematic.