I don't know what the rules are at the museum but the NSA had a booth at the RSA conference this year and they brought an Enigma with them. They allowed me to use it and it seemed to be in full working order. Dials rotated and the keys made the lights come on. You could even open it up and see the internal mechanism. It was an amazing experience to physically touch a piece of history like that--one of the highlights of the conference for me. A colleague of mine who is fluent in German was reading the instructions which mentioned that there was a printer that could be used with the device--something I hadn't heard before.
We owe a great debt to the code breakers at Bletchley Park like Alan Turing and Gordon Welchman and the Poles like Marian Rejewski who paved the way for them. Not only did they help win WWII and save countless lives, but they also planted the seeds for modern computer science in the process.