Quit mucking around with the stock system and just put something else on. I loved my G-Cat system. Extrememly simple and easy to use, but the housings snapped when a storm flipped the boat over on the beach.
I put on a Dotan Sampson 25 system, which does steer the boat well but it really only has three positions- all the way up, all the way down, and stuck halfway in between. Also, it can be difficult to lower one rudder without raising the other. I don't really like the system that much.
My friend put a Hobie system on his Prindle 18-2 and absolutely loves it. That will be my next rudder system when I can afford a new one. My Dotans would be great for dingy sailors.