Hi Beatnik
I assume the "XB" is XB-Game-Over-Relay. I assume Your snippet (I show here again) has on top: "Number-Match-Replay-wiring" --- do You ever get "No-Match Replays" ? You may have changed the pin to "NO No-Match-Replays" (?). IF (if, if) You do get No-Match-Replays: We can say "all good from out-right leftbound through blue-1,2,3,4" and the investigation is on the "5,6,7,8,9". You wrote "10,11,12" is good.
HowardR lately came up with an VERY GOOD IDEA --- a Jumper-Wire has on one end an gator-clip and on the other end a "Safety-Pin". We can move the tip of the Safety-Pin almost parallel to an existing wire in the pin - insert the tip of the Safety-Pin into the fabric of the insulation of the wire - into --- inserting almost parallel - push-in --- the Safety-Pin is mounted, inside the fabric the tip of the Safety-Pin touches the metal wire. A great idea and it works.
Please say "I want to do tests - I accept when the pin acts abnormal - but from the behaviour of the pin I learn about 'specific wiring is good (or it is no-good)' ".
When You mount an Jumper-Wire "like my green line" - inserting the tip of the Safety-Pin into wire-BL+BLK near the Ball-Count-Unit --- other end You clip-on at "Switch on Tilt-Relay". You start a game and play --- when the pin steps to the last ball: WITH this Jumper and the connection through the Ball-Count-Unit is good: You MUST get "Game-Over".
When You mount an Jumper-wire "like my red line": You will get the last ball and probably can make some simple points --- as soon (in the last ball) the motor is made to turn (You make 300 points so the motor turns): You will get "Game-Over".
Then "like my brown line" and "like my orange line": More tests.
The idea is: With a Jumper-Wire jumpering part of the original wiring - what does the reaction of the pin tells me ? Greetings Rolf