I decided the rudder mechanism needs to be adjustable. The way it is now, you have to set exactly the right angle for the rudder in neutral (no drag position) and then wrap the control cable around the hang tube and tape it in place so it's really set during construction with no easy way to adjust it once the glider has been built. Here's my idea of making it adjustable without adding heavy turnbuckles.
Replace the existing front stop (appears to be made out of Delrin plastic or something similar) with a stop that is slotted.
Wood was the only easily obtainable material for me so that's what I used in my first prototype. The cage tubing is 2 inch so I started with a 2 inch Forstner bit for $9 at my local hardware store and drilled a hole through a piece of hardwood block I had laying around. Cutting it down to something close to the original stop piece I then used a router to cut the slots for the machine screws I used. I drilled out two of the mounting holes for the original piece in order to accommodate aluminum nutserts I bought at my local hardware store.
The original stop:
Nut serts mounted in only two of the drilled out original holes
The slotted replacement stop block prior to sanding
The finished replacement stop block mounted using two machine screws.
I chose the hole set that best lined up with the middle of the range of final adjustment I was looking for on the rudder. I got lucky and ended up with the block set right in the middle of the slots so I can adjust either way. I'll probably tape some tell tale yarns on the rudder to make the final adustment.