Page 7 of the Instruction Manual explains an "Extra Ball Relay Assembly" that was available to operators upon request. This "kit" would change the mode of the game from Replay to Extra Ball, awarding one extra ball per ball in play instead of awarding replays. The relay would be mounted on the lower cabinet board in a vacant space provided for it. It plugs into a nearby jack. If this relay was not installed, a shorting plug was necessary in that jack to provide for replay operation. The schematic diagram makes dotted-line reference to the Extra Ball Relay at locations F-7 and F-15. Two earlier Williams games which have this optional relay are 1965�s Big Chief and 1967�s Shangri-La. The Sample playfield shown in this listing has the light blue upper apron and wood rails, as does the game in the flyer. It is installed in a game with a cabinet serial number 61361. Both the game in the manufacturer's flyer and the Sample game pictured here have the left drop lane identified with artwork showing a lantern with the words 'Closes Left Gate' while the production version shows no words inside this lantern. This suggests a wiring change was made for production games or, perhaps, no wiring change was made and the words never applied to the Sample game, indicating an error was made when those initial playfields were ordered. The Sample game has a triangular plastic above the center target, smaller than the five-sided plastic that appears on production games and which required two additional posts. It would appear that this change was to provide more rebound surfaces for longer pop bumper action.