Ford mate,

Do yourself a favour and go buy an ANALOGUE meter.
 For an EM repair, id say these are essential. Reason being that you can put clips on the leads and clip them into place on a relay/ switch.
 You say that switch 4D and that it opens and closes. This may be the case, but is it making electrical contact whilst doing this??
 The way to find out and to eliminate every switch in the start up sequence is to clip the leads across the switch and have the meter set to low Ohms. As the game goes into start up sequence watch the needle on the meter - you should see it shoot over to the other side of the gauge for a split second as the switch closes - this means that it has low Ohms or made good contact. If you do this with a DMM then you will not see it as the damn things are DIGITAL and so are always slightly behind what has just happened. You need to ensure GOOD contact in the start up sequence.
 Do what i have described for the score stepper also... if the needle dont move or only moves very slightly, then this is a fault and the leaf switches need adjusting.

Im scratching my head here... have you honestly gone some 50 odd pages fixing an EM and you dont own a meter?? Man!!!! You could have had this licked 49 pages ago!

Gav, My only problem with having a multi meter is i have no idea how to use it  . I would even know where to clip the leads on 4D to check for contact.. im an electrical idiot