I guess so, but the wheel is actually wobbling on the steering shaft on my 420. So I took it off and noticed that the bearing/bushing inside the steering wheel is loose it seems. I hope I don't need a new steering wheel.
There are three adj. on that steering box all difficult to do in chassis first is the pivot that the steering arm moves on double nut I think 15/16 wrench back off the outer nut tighten the inner and check for binding then tighten the outer lock nut. Next is the slotted head screw with a lock nut on the same side as the large pivot bolt a couple inches away same procedure as the first, then there is the threaded end plug you describe usually dont need to do that one unless you have end play. These adj. are difficult because it is very close quarters in there. I usually pull the coulmn out take it apart clean all the old hard grease out and inspect the bearing's and gear's then do the adj. on the bench. I have done several and only one had bad bearing's. It is also a good time to repaint the tube. It sound's confusing but is very simple. BILL