I finally had enough and pulled the side plates off my Lee 4-20 so I could fix an annoying problem.
The handle that operates the nozzle slides up and down on two screws that act as guides and limit the travel. The upper screw constantly worked its way out of the side plate and caused the handle to move too far or get hung up. The problem is that screw just has sheet metal type threads that engage an extruded channel inside the side plate. There just isn't much there for the threads to engage. It is a classic example of how Lee found a way to cut costs.
The quick fix was to just use a pair of pliers to compress the sides of that channel so that the threads had a little more purchase.
I think the next time I have that apart I'll fabricate a more permanent solution.
On a positive note, about a year ago I polished the nozzle seat and the tip of the metering rod and that stopped the dripping.
At some point in time I'll replace the 4-20 with a RCBS Pro-melt. For now I'm making the cheap Drip-O-Matic work.