Bill, I used to own that guitar in your pics, serial #1200. It was 5+5 when I got it ~2013, I just sold it recently.
I spoke with Don Fritsche when I first received it and he told me that the way they fabricated the original push rods (the heavier fixed section that connects to the bell crank at one end) was to grind a square tapered key on the end (see pic below), then heat the rod with a torch and drive the nylon end on such that it begins to melt and bonds firmly to the rod. The pic below is one of their originals, dismantled, actually a leftover from the same guitar in Bill's pics above. The nylon ends are 1/4" round x 1-1/4" long, the rods are 0.156", 5/32"Ø (which I believe is what Bill meant to say above). They would pre-drill a through hole in the nylon piece first that would slide over the heated rod on one end, and also provide the hole for the tuning push rod to thread into on the other. The original threaded actuator rods, the ones that go through the push fingers, are 1/8"Ø w/ 5-40 thread.
Lyn, I believe you could re-attach the displaced nylon(s) using the same method Don described to me, just put the rod in a vise or something and heat the end to near red hot, then press the nylon back on, far enough to bond to the rod. Alternately, a little JB Weld or similar epoxy would do the trick too. You can attached the fixed 3/16" tuning nuts using similar methods. If you've got some that are displaced you should be able to see the square tapered end like in the pic, unless the bad ones were someone's DYI units added later (which might also explain why they failed).
The wire wrap that stops the push spacer can also be just a small cotter pin or something similar, but I believe the wire was used just keep the overall assembly as compact as possible so that they won't hang up on adjacent rods when rotated. Keep in mind that once you've assembled these you won't need to mess with that connection again until you decide to change your copedent. It's not something I'd worry about (I didn't). Perhaps it's not perfect, but it's a really good system as designed. One other thing to note if you're fabricating additional rods, ideally the connectors should to be of staggered lengths on adjacent strings to avoid potential conflicts where one rod would rub against an adjacent lower and unintentionally activate it, and to avoid collisions or interference with adjacent bell cranks on the first two or three cross bars.
Also, you will
not want to replace the nylon ends with metal threaded couplers as you suggest in your last paragraph. The same person designed both, but this is a completely different system than a ZB. The nylon couplers are an important part of the design. They function the same as a standard nylon tuning nut at the end on a typical all pull guitar rod, or on the raise end of your guitar - the tight fit and relative softness of the nylon is what keeps the rods in a stable position tuning-wise. A threaded coupler with a lock nut would require you to reach under the guitar and loosen, then re-tighten, the nut for even the most tiny and incremental of tuning changes. The tight fit of the nylon connector makes it so you always can tune the lowers reliably from the end plate without ever having to reach under the guitar. One other thing I will say about guitar #1200 in Bill's post, it had virtually no cabinet drop, and the extended tuning stability for the pedals and levers was the best I've experienced on any guitar I've owned. Rarely needed a tweak.
Good luck!
