Wow, what a great find - congrats! I've been looking for a Sega game from this era forever.

Make sure that even though the score reels are at zero that the contacts for each reel (that most likely close at the zero position) are actually closed (and you can get continuity readings across them). Also make sure the outhole switch is closed when the ball is resting on it (and you're getting continuity across that switch).

You could also try manually triggering the start relay to see if you can at least get a game started.

Good luck, and please post some pics if you get a chance!

Edit: Not really what I was expecting to see in the backbox. Looks like the score reels may not use the traditional switches I was imagining but more of a wiper system. I usually use the green scotch brite pads to clean these:

http://www.ipdb.org/showpic.pl?id=44&picno=59669&zoom=1

This is a good thought. If you look at the pic on IPDB, look at how dirty this unit is. On some older EM's, you have to sit and play with these units for hours to get them to behave like they did when the game is new (meaning moving freely around in circles when triggering it). Also, make sure to clean the wiper contact plate with a green scotch brite pad or equivalent. If these brass contact points are really dirty (on any of these types of assemblies), the game will never work correctly.

You could try manually ejecting the ball into the shooter lane once everything resets. Maybe the coil's burned out? Also, sometimes there is a switch that's triggered once the ball is shot from the outhole to the shooter lane (although I have no idea if there is with this game).

Great news, and congrats on bringing a piece of pinball history back to life!