The machine below is a strange one and must be one of the first using a magnet based coin acceptor, but oddly on top of the existing coin escalator, of course giving the odd tall tower.. Weird looking set-up and one can only assume added more complexity and problems...as per the text below. Did not last long and actually slowed up playing the machine going through two coin mechs and counter achieved the potential turn-over, by slowing the rate of play, even taking into account the few slugs that were stopped.
This is a rare Mills Tower Castle Front that was developed by Mills in order to make cheating difficult, if not impossible, in casinos. As a coin is placed in the slot, it travels a course through the tower which is filled with magnets and other slug detectors and if it is a good nickle it finally arrives in the escalator and the machine is then ready to play. Given the age of this tower and that its sole purpose was to stop slugs, it is amazing how well this slot works. The tower is complete with various methods of stopping slugs and other counterfeit discs that were used to cheat the casinos. Although this early example attempted to stop slugs, it wasn't until years later with the development of optical character recognition, that almost all cheating at slot machines was eliminated. In looking at picture 6 of the tower note the various use of magnets and other devices that were used to stop slugs mechanically. Regardless of whether this slot was ever used by the casinos, it is the opinion of many that the additional time it took to play a slot machine with these devices, it was more costly to the casinos in revenue than if they let the cheaters play and caught the majority in the due course of business.