I built a 601XL-B. My nose wheel suffered from the same problem during the build. Mine was due the clamping force of the bearing block. To avoid re-machining the large hole, I added one 0.016 aluminum shim as a sandwich between the two halves of the block to slightly relieve the clamping force. This has worked well for 6 years and over 200 hrs.
I did not paint the nose strut at the point where it passes thru the bearing block. Here, I use grease. Also, the torque on the pass thru bolts are snug, not crushing, or the bearing block deforms.
I'd check the bungee. They can harden with age. I replaced mine and it reduced the turning forces by half. As for the centering function, the all flying rudder can get quite unruley without the dampening of the nose gear linkage. A couple folks on this site tried various things over the years, including completely uncoupling the rudder. One fellow that tried it was seriously afraid he would lose control of the aircraft. And no, you are not the only one Zenith is no longer communicating with as several builders that I know cannot get responses from them. I don't know what's going on with them.
Hi Harold, i agree on your HARD steering , I build a CH 750 and sitting on bare metal with out Back support it is VERY to push the Peddles so hope ones we are finish and Engine in that it will push the Centering Block a bit away so it will be better , not there Yet...Eugene from Zambia Africa
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