Quoted from Garrett:

I know it's generic but should help. My Aztec manual deosn't say a whole lot about the start up sequence either.
From CFH,
http://www.pinrepair.com/em/index3.htm#start
Williams Start-Up Sequence.
When the start button is pressed, the credit unit is decremented. This is done through the credit unit zero position switch and the 2nd coin relay (and the ball count zero position switch).
The end of stroke (EOS) switch on the credit unit decrement coil will energize the coin relay.
The coin relay will trip the game over relay.
The coin relay will energize the reset relay. The score motor will run.
The reset relay will energize the ball count unit reset, through the score motor.
The reset relay energizes the 2nd coin relay latch and game over relay latch coils.
The reset relay will energize the score reset relays, through the score motor.
The score reel reset relays will zero the score reels, through the score motor. The score motor will continue to activate the score reset relays until all the score reels reach the zero position.
The reset relay activates the bonus unit coil until the bonus unit zero position switch is activated.
When the bonus relay drops out, the outhole relay is energized through a different bonus unit zero switch and score motor switch.
The outhole relay will run the score motor. The bonus unit will step up once. The ball will be kicked to the shooter lane.
Following these sequences step by step, you can usually generally locate the start up sequence problem. For example, say you have a Gottlieb multi-player game. After pressing the start button, the score motor starts turning, and the score reels all move the zero position. But the score motor keeps spinning and nothing more happens. Looking at the start-up sequence, we can see this would probably be a problem with the "SB" relay and the player unit (or maybe a dirty score reel zero position switch, which occurs in the previous step).