I thought an expert would chime in by now. as for the plastic adjustment screw, you may end up drilling it out. I believe I've seen a thread about that.
As for adjusting the tiller connector, you want the leading edge off the rudder and trailing edge to be about the same. That's were you would take your measurements at.
Make sure you have the rudders on the correct sides before you start.
There is a good you tube video on rudder adjustments.
85 Hobie 14 Carumba
83 Hobie 14 Corando turbo
89 Hobie 14 white prism
80 Hobie 16 tidal wave
83 Hobie 16 blue Hawaii
84 hobie 16 Yellow Nationals
85 Hobie 16 white/blue
eventually I may get it down to 3