I just replaced a bill validator with a rebuilt validator that I got back from hamilton from repair. It seems to shut down quite often from the tamper prevention option that these bill validators have. For the time being I set the disable timer to zero because I can't afford the thing shutting down all the time when cars are lined up. I know hamilton says to make sure the validator is secured which it is, all the screws are tight. My question is how does the validator determine if someone is trying to cheat it? Is this disable timer more trouble than its worth?