artbyaccident, thanks for the awesome pictures and write up! It's amazing how much pictures can do to clear this kind of thing up!
A little information goes a long way...i headed over last night for some shooting and another stab at this. As i pulled in to his drive, he pulled three perfectly formed cases out of his pocket. I think we just had the wrong mental picture of how the thing was supposed to operate, and after getting set straight it all came together very quickly.
Thanks again for everybody's help! It's a testament to the kind of folks at TFL, plenty of patience and lots of good help for what's obviously a rookie issue.