Hi 80spit
I do not have a schematics "Bronco" --- I look in the one of "Surf Champ". The "L-1000-Points-Relay is for the 1000-Score-Reels and at the same time for the 10'000-Score-Reels.

I can offer an explanation - "IF, if, if" - 1000-Score-Drum of player-1 AND 1000-Score-Drum of player-2 are (accidentally) BOTH on position "9": The Switches "P1A" AND "P2A" are closed AT THE SAME time - one of them is entitled to be closed --- the other one is faulty closed (my theory is a bit crummy).

SteveFury made an excellent topic - he starts with "basics" and from post-30/40/50 on he talks rather "specific Gottlieb". To store a link (so I can find the link) I wrote post-94 and post-97: https://pinside.com/pinball/forum/topic/em-pinball-circuits-basics-to-not-so-basic/page/2#post-3402051 and mentioned http://webpages.charter.net/chibler/Pinball/Images/CamPositions-4Player.jpg .

Go to the backbox and look at the Player-Unit - look towards the players - look along the axle of the Player-Unit - see Steel-Ratched - then Cam-1 - then Cam-2 --- and on the bottom of the page: See the Switches named "P1A" and "P2A" --- want to investigate in these switches ? Greetings Rolf

0Surf-Champ-Work-15 (resized).jpg