Check with Cabrinha, I think the part you need comes complete with the trim system, it's not just a case of getting the stopper ball and putting it on, so worth seeing if changing this affects the kite at all, although I don't see why it should? I looked at getting a replacement on my 2008 kites but couldn't source one, I think that'll be your main problem, unless you have an old one to hand.
I have the 2011 IDS kites ones and don't find the problem you have with the recoil, I think it was a great innovation, there just seems to be enough tension to keep the kite flying when you unspin, maybe unspin a bit faster
. I also find the spring much better in the waves than the old stopper ball; if you miss a trick with the recoil the kite stays in the air for quite a while and this extra second or two allows you to regain control. I found with the old stopper ball, that after time, it would always pop out, unless you really cranked up the tension. All mine eventually wore down and stopped working anyway. Less bits to wear out and break on the recoil in my opinion. Is the tension ok on the spring .. not too weak??
Not sure about your lines or chicken loop query, sorry