The ACW-4/5 uses a 110 volt validator. There are 3 things that could be wrong. The cycle inhibit relay box could be bad, the bill box lens could be loose or the bill box is not sitting on the validator correctly or the validator needs to be serviced. The 110 volt Mars validators have a capacitor on the main board that needs to be changed every few years. If it's 3 years old it's about time for a good overhaul, not just a belt change. When you say you reset it, how are you resetting it? Cycling the power On and Off?