hmm, Your topic in EM-Hangout - I usually visit the EM-Tech-Forum.
Great - ipdb has the schematics and the manual - look here https://www.ipdb.org/files/2104/Williams_1969_Seven_Up_Instruction_Manual.pdf on page-11 (on the right side - original-page-29 (?)) - Reset-Relay - Switch-C is for the 10-point-score-drum, Switch-D is for the 1-point-score-drum. See the first JPG - on the bottom: Wire-Black-White runs from Score-Motor-Switch-Impulse-B to "RESET-Relay, Switches C and D". Then run(s) wire(s) to Zero-Break-Switch(es) on the Drum(s). Look in Your pin at the Reset-Relay and the switches - then check wire-color-B-O and wire-color-O-Blu --- truely soldered-on ? See the first JPG - on top: I believe the actual wiring is as I show it - a short Jumper-Wire hops from one switch on the Reset-Relay to other switch on the relay.
I concatenated the ipdb-schematics - (heavy) freshened up --- see the second stuff - the PDF - to look at: You may have to make You an copy (down) on Your computer. The problem with "such heavy freshening-up": I may make faults / errors --- ALWAYS have the original schematics to look up there when You run into troubles reading "my work". Greetings Rolf