I have to say it "Score of the century" well done ! 

Just a quicky,:
Unplug/plugin the score display #1 connector on & off the display about 10 times...
The abrasion of each plug/unplug will clean the connectors to make them conduct again.
You might be lucky to see score #1 come to life again....it might be *that* simple 

Also unplug/plugin the connector on the main score board too, maybe it's not passing score #1 addressing info through to score #1  ??

(i've fixed a few machines this way myself).

once again, what an abolsute score (no pun intended).
Marty.