All mechanical devices will fail eventually. While a test actuation might reduce the risk somewhat - its not going to be a sure thing. Remember the table didn

All mechanical devices will fail eventually. While a test actuation might reduce the risk somewhat - its not going to be a sure thing. Remember the table didn't kill the last patient that stepped on it - why would anyone suspect the switch would fail now. Mechanical failures need to be dealt with differently than software. Parts must be replaced before they fail. Even if they appear to work correctly. Software doesn't wear out so its a whole different ball game.