Designer Bill Pfutzenreuter told us that about a dozen (or less) sample games were made, followed by approximately 100 prototype games, before regular production began. Up to this point in manufacture, the Dalek head in the backbox topper moved from side to side. As a cost saving measure, once regular production began, the motor and front-facing opto for this movement were removed, resulting in the Dalek head being stationary (non-moving) on production games. The wiring and software for this feature was left intact, and this has allowed game owners to reinstall the missing components, either by purchasing after-market kits or by purchasing the components individually, to again make the Dalek head move from side to side. We asked Pfutz if he was aware of a way for new owners of this game to discern if their moving Dalek head came from the factory that way or was retrofitted. He said that Williams had glued the stationary Dalek head onto the body, therefore the kits had to "unglue" or cut the head off, and that it was complained that Williams had used too much glue. Thus, perhaps one could look for any irregular cuts or glue remnants. If anyone knows of additional ways to positively identify retrofits, please contact us. In this listing is a playfield identified to us as a prototype "machine number 2". It has several artistic differences as compared to the production playfield, including: The doctor's cape in center playfield is a solid color, not tartan. Some of the Daleks are a different color with different ball colors. The upper right ramp decal is one red arrow, not two yellow arrows. The playfield is Diamond Plate. The game in the manufacturer's flyer has a ramp decal showing the single red arrow while all regular production examples in this listing show the two yellow arrows on this ramp. Also pictured in this listing is the upper playfield from the game with serial number 060031 which has the single red arrow. Based on the many other serial numbers identified in this production run, we have labeled this game as Early Production.