Even new can be defective, with everything these days.
As for the sweet spot, if some folks don't know, it takes some practice to find.
Pull the rope until you start to feel the compression feedback through the rope, pull just a bit more, you will feel the rope start to get slightly softer, then a quick yank.
Takes a couple of tries, then you will do it from habit. Give it a go and you will save some money on recoils and chiropractors.
