I know way to well. Fast and simple is if it came with it, it has to be functioning the same as when it left the factory. If you start changing the door locks system, you will need to meet the 2010 spec, so basically you cant run the spindle with the door open at all. The biggest problem have been the taiwan/China machines. If they were available from the factory, whether your machine came with it or not, it's supposed to have it. Now, larger machines are exempt from door locks, as well as any machine that doesn't have a automatic tool changer. There are several pages of rules in the ANSI, OSHA, and NFPA about it. EC has there own. It's a long road to go down.