Hi mike and thanks heaps for the pics, I see now what i am missing.....just to confirm there is only one nut, that is the lock nut which is that long socket type nut with some thread at one end only? I actually found it under the spare tyre but it was stripped wouldn't stay on

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What I need to do:
1. so is this what I need to replace or can any nut do?
2. all I do is tighten it (clockwise?) the manual states... loosen lock

of counter nut on gear unit, hold shaft in place with screw driver & keep tighting counter nut, what does it mean lock of counter nut (another nut)?...
Thanks again