You guys should do what my club does, a 3/4 thick steel rod holds your target or cardboard (staple target to cardboard). Makes a hell of a sound if you hit the rod and I have seen a bullet deflect straight down, cut the target in half and go flatten itself on the concrete floor.
It's not the actual target holder that is the problem. It's the string that shuttles the target up and down range on the track.
Personally, I've never had a problem with the current system. And every time I need to get a clear to go down range to pick up a fallen target, etc. I check the stuck lanes. Usually, it's not even the string that's broken... just the carrier getting hung up on the track at the joints.