Check the switch on the 9th position of the 10 reel. I suspect that it is closed when is should be open unless you are going between 9 and 0. (around 8F on the schematic). or-blk and gr-wh-red wires.

Capture (resized).JPG

I would trace the #2 target relay wire for bare wires touching the 10 point circuit. Check the Jones plugs for solder beads or the play field around the #2 target.
Long shot make sure the#2 target has the right gap. I think is does otherwise you get random 100 pt scoring vs just when 10 points score.