ORIGINAL: Scar
The EZ connector's screw will bite into ordinary, soft, threaded pushrod wire. It won't bite into Music wire, which is heat treated to be hard.
That makes sense and explains, I believe, my bad luck with these connectors. They were used on an older ARF that used thin music wire for pushrods. The problems were probably a) hard music wire and b) thin wire that didn't leave much surface area for contact. Thanks for the info!
Mark