I have worked on these doors for years . The right angle gear is the main problem with the combo lock. The pin in the gear loosens and move starts and it all down hill from there. The locks on these doors are on the wall behind the the viewing station. The door is locked with a rod system. The vault alarm is a vibration type. That hook up to a control that floods the vault room and area around the vault floor. thats the basic over view of that type of vault. TJ