Had to go deep into my old binders for this one. When this board was designed pins 14 and 15 could not get to their destinations via normal traces. The system ground plane was in the way. Pin 14 is a logic ground and pin 15 was the unregulated return. They used the zero ohm resistors to bridge the ground plane. If they had used jumpers it ran the risk of shorting out if these were mishandled, as was common with distributor technicians. There is no designation for them on the Bally schematic and parts BOM that I can remember. They just left them out. When asked they just kind of played it off as we should know better.

They are wattage rated so they will burn through and act as a fuse in some cases.

In distributor training service schools we used to go over the schematics line by line or section by section. This was different from service schools at vendor locations as those were rarely more than one day. At the factory you were there for a week most of the time.

You can use the William's part number if you need one. On the system 7 schematics, (that's how far back I had to go for these notes), the part number was 5010-09534-00. 1/4 watt.

Hope it helps