I agree with Martin. What you are feeling is the drive wheel, with its gate, rotating around and picking up the next wheel. It has a protrusion that, when rotated almost one full rotation, will pick up the next wheel. Thus the free movement. ie. Situation normal.
To manipulate these locks you only look at the angle of the key. This changes when the gates (slots in the wheels) line up with the lever being pushed in by the key.
You could start here. Scroll down to the "Direct Entry" locks, and look at the videos listed.
viewtopic.php?f=36&t=68049Cheers.