Thank you for taking the time to characterize and describe the problem. You've made excellent observations. What should likely happen next that isn't happening is that the O/Ball Return relay should fire because the ball has closed the Outhole switch. The O/Ball Return relay in turn fires up the score motor which in combination with a switch on the O/Ball Return relay should fire the Ball Return solenoid and serve up the ball. There are several switches that need to close to get the O/Ball Return relay to fire. I'll leave that as an exercise since you just wanted some direction.

The reason that most of the playfield is dead is because the game hasn't completed its reset sequence (the ball hasn't been served up yet). There is a switch under the ramp between the outhole and the shooter lane that advances the Ball Count Unit. Once that advances from its reset position the playfield should be active.

The reason the saucers are active is because they're the only places the ball can get trapped on the playfield. They make sure that under any circumstances (tilting, cycling power, etc.) the ball is ultimately returned to the outhole if there's power.

/Mark