I see the problem with the shellplate rotating halfway only once every roughly 100 pulls of the handle. If there's a damaged part in there, wouldn't it cause more consistent problems than this?
I can do this with mine on purpose,and don't think this is either a defect or a problem. In fact, it is very handy.
The indexing screw is on a worm gear. You can turn it all you want. Just follow Lees directions. YOU READ THOSE, RIGHT?