Sounds like your stepper units need to be serviced... they should step up and step down easily; you can manually test by moving the coil plungers on each unit, mimicking the movement made when each coil is energized. While you're at it you should clean and then apply a light coat of super lube to the bakelite disc that the wiper fingers move over.

That game uses quite a few steppers - credit, ball count, match, coin.

Here's a good place to start learning about EM theory of operation and steppers in general; There's a lot going on under the hood of this game, including the large relay bank under the playfield that keeps track of each player's made balls; I've restored one and know from experience what a bear it can be:

http://www.pinrepair.com/em/index.htm

http://www.pinrepair.com/em/index2.htm#steps

You'll need a schematic and follow paths for game over relay trip, and ball count unit reset. I have a schematic but not handy...

you should invest in getting the schematic from Pinball Resource... I have a feeling you're going to run into other issues as you fix the ones you currently know about.