ive personally fitted over 250 enforcers, 6 in one week alone, only had 2 faulty panels, 3-4 door contacts faulty, 5 of the old style square keythobs, 2 or 3 pirs but possibly 10 bell boxes with tamper faults which appeared to be due to the **** lid tamper switch, i now adjust the switch completely different and have never had a single bell problem in last 20 months.