Also, green PCB's - It's a SAMPLE, not a Prototype.

Protos are usually extremely limited in number - under 10, sometimes as little as 5 machines. They're made with red PCBs, and are kept in the company usually in the developers, designer, programmers offices to work on.

Samples are the first run of the games from the factory - between 100 and 300 made. They were usually sent out to high-sales distributors to get out to locations. These locations then had to provide feedback to the distributor on how the game performed, so the developers/designers could make changes.

Usually by the time the samples are out, large changes (wiring changes, such as adding lamps or switches) aren't often done. However, switches can be removed often.

Examples - the far right loop switches in WCS94 were removed mid-sample run. The door flashers in TZ.

Proto to sample changes would be the red lamp insert colors in TZ (Camera & Dead End), the "Ultra-Ball" changing to "Ultra-Goalie" in WCS94.

Sometimes bigger changes are needed during sample runs though, like having to add 'SPIN' to the inserts on the spinner on CV.

It could happen, for any number of reasons. The prototype WCS94 playfield I just picked up isn't dimpled, nor ever installed into a game. (A situation that makes sence is that an artist making changes to a playfield wouldn't need the whole game, so he just had the field hanging for reference. Or, the company ordered an extra field "in case"..)