There is no zero jones socket. They go from 100 to 1000. See attached schematic fragment.

I find this very surprising. If you're sure of this, it would indicate another problem.

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One nice thing about the match circuit is that you can test and experiment with various combinations using a meter with the power off. If you clip the meter to the orange+green wire on the 1000s score reel and to the red-yellow wire on the 100s score reel the meter will tell you whether there is a path between them (and through the high score adjustment plugs). Low resistance or even continuity will work in this case since there is a normally open switch on the L (100 point) relay to block the other path through the transformer. Then with your meter in place you can move the two score reels and jones plugs to various combinations to see if there is a good path through them.

Keep in mind that the the path will be there when the score reels are 100 points less than whatever you set on the jones plugs. For example if you've set the award level for 3800, the path will be there when the score reels show 3700 because the path will be used the next time the L/100 point relay fires (to 3800) and closes the L relay switch.

/Mark

"One nice thing about the match circuit...", should be "One nice thing about the High Score circuit..."