David,
I'm very interested in your posts of your A-4 problems, especially of the nose steering problems. I'm having similar problems with my A-4 project (Skymaster). Skymaster, Laiki, BVM, et.al. will not answer my emails requesting parts for the A-4 landing gear. I have dammaged the pistons in the left and right main gear units trying to operate them hydraulically. But that's another story!
Correct me if i'm wrong but i believe that the CARF as well as the Skymaster nose gear steering operate hydraulically. On the surface, this method has good promise of being friction free and very positive with "0" slop. It should operate like any common Automotive/motorcycle hydraulic clutch system. But a little bit of air in the system is a "deal breaker". I have spent literally hours on my system trying to remove every last air bubble but somehow air always seems to creep back in. I noticed on one of your photos what looks like a fairley large air bubble in the line. I have found that a bubble this big in my system renders the steering very sloppy and unresponsive ,especially with weight on the wheel. Since air is easilly compressed, the servo/master cylinder uses quite a bit of travel just compressing the bubble. Ball bearings are not the answer, when the airplane is not moving the increased friction is not in the system but skidding between tire and ground. Like trying to steer your car with the engine off. The servo mounted on the wheel end of the strut looks goofey. I think we can solve this problem ourselves if we can find a way of keeping air out of the system. When my system is air free it is very solid and responsive - it just won't stay that way for very long.