I agree, the zip is a good idea. I don't doubt that it is an equipment malfunction (poor design, whatever). What I am curious about is why this doesn't routinely occur for all of us turret users. when I clean mine, the hangup problem simply goes away, but that solution doesn't work for some of us--as editingfx and John Wayne can attest to.
I've never had to polish / break edges, whatever--just keep it clean. When it starts sticking in the shellholder head, it is because of grunge buildup on the back of the arm--which thrusts it "forward," so it binds against the side of the shell holder primer insertion hole. Occasionally, I get brass slivers and fine debris from the PTED die operation on new cases, and it builds up a bit on the shell holder (like you can see in the latest pictures by editingfx). Cleaning it off with GunScrubber and carefully cleaning the slot (for cartridge insertion) in the shellholder and maybe the primer arm hole in the holder does it.
Today I loaded 100 rounds off my turret it had been cleaned about 25 rounds, maybe 50, before that. Since cleaning, it hasn't hung up. Those 100 rounds were uneventful.
I'm wondering about Lee's machined tolerances in the ram slot, the position of the pivot pin, and the finish on the primer arm. Whatever the cause is, it's good to see multiple solutions availble for application as needed.
added on edit: I agree, the primer arm will fall out when the ram is raised, if there is no shell holder in place. With my workflow, there is always a shellholder in place, so that's not an issue. Of course, on the occasions when I am loading pre-primed cases (like for by novice .223 work), I remove the primer arm before I ever start.
Jim H.