The rollover switch should close to connect a red+white wire and a white-brown wire, which should cause the ball gate relay (relay EX) to pull in. Once the EX relay is pulled in, it will stay that way as long as three other switches are all closed: a normally-open switch on the EX relay itself connecting a white-brown wire to a white-orange wire, a normally-closed runway (i.e., shooter lane) rollover switch connecting a white-orange wire to a white-green wire, and a normally-closed switch on the P relay (add player unit relay) connecting a white-green wire to a red+white wire. Make sure all 4 of those switches are opening and closing properly.
Hope this allows you to correct the problem. I put a post on your other thread recommending that you get both a schematic and a manual for the machine. I get mine from Pinball Resource. It’s money well-spent for resolving issues as they arise.