Since your game sat idle for so long there are going to be plenty of intermittent issues (dirty switches, poor connections, etc.) that will make chasing down individual issues that much more challenging. Be prepared for each resolved issue to uncover a few more issues. Those who have restored a few games might consider carefully going through everything before doing any troubleshooting but that's not recommended for those who are less experienced since they're more likely to introduce more problems.

I'd recommend addressing the simplest issues and circuits first and getting them reliable then going after some of the more complex stuff. So for example, hitting the left flipper should fire the Lock relay (at 11E on the schematic) which should remain active until the game is powered off or the Delay relay fires. The Lock relay holds switches closed (at A2) that send power to the game lights.

The coin handling circuitry has many options depending on which coin slot you use and the pricing set for the game. For now just get the 1st Coin Chute (at 4C) switch to fire the Coin relay (at 4E). The Coin relay in turn should close a switch (at 9D) that gets the Score Motor (at 10F) to start running. Once the Score Motor starts running the Coin relay should relax and the game should start resetting (clearing score reels, etc.).

Keep in mind when troubleshooting that a switch that closes mechanically is no guarantee that it's also closing electrically. Soot and oxidation build up on unused switch contacts and can provide more than enough resistance to prevent the circuit from operating even when contacts are touching. Jumpering around suspect switches or testing them with a meter are good ways to check them. If using a meter always measure resistance, not just continuity. A closed switch should have a resistance of about an ohm or less. Coils and transformers can have resistances that are low enough that meters will often report continuity. A common mistake is to assume that the continuity is through the switch rather than through some other path around the switch through a coil.

/Mark

The Delay relay only fires when one of the slam switches closes indicating that the game is being abused. Normally it shouldn't affect starting or playing a game. Details are in the manual.