The present invention relates to security system for a gaming apparatus and method for its operation. It further relates to a gaming apparatus incorporating an electronic security system. The gaming apparatus includes one or more physical displays that rotate about at least one axis. These displays are physically associated with a mechanism that controls the odds of the reel stopping at any particular reel position in such a manner that the probability of stopping at least one position differs from the probability of stopping at least one other position. The security system provides a safeguard against unauthorized alteration of the machine parameter that could effect its outcome. The present invention is particularly appropriate for application in slot machines.