Im trying to keep this simple here.
We HAVE to assume that the wiring is all OK until we have eliminated all other possibilities.
Im clinging to the time when you opened up the "A" player leaf switch. This allowed game to bust at 30 NOT 20 as it should... so with this switch open - logic is good.
There is NO path to ground on 20 points... not one that would fire the bust relay anyway.
So im thinking that at 20 points there is a short on a wiring or the stepper that is linking the 20 and the 30 together.
IF this is the case, then ground is given a path directly to BUST... we dont need 8 Re or 9 RE or even RO RE... it goes straight to bust relay and coil. And if im reading correct - you have verified the correct operation of 8,9 and RO
Make sure your wiper is not touching both contacts.. im assuming front and back are active on this.
Also lift the contact arm and test between increment 2 and 3... should be open.
Drop contact arm and test again - should still be open.
If the above tests OK, then its getting hard as 20 points is completely isolated from BUST
Also.... the game does start at zero yes?? It doesnt give 10 points at start up does it?
