I used to have similar problems as well, and did hate the system too.

Before I was sailing my Nacra 6.0 I owned a Dart 18 and I must say they do have the perfect system.

I solved the Nacra Rudder Problem by replacing the lines inside with the original ones (bought from the official distributor in Europe) and although the waters we sail in are not very deep. (we often hid the ground ) it is working perfect for me.

This summer I took the picture below at a marina, did not have the chance to speak to owner and ask him if it works.