How do you tighten the LCA shaft?

What nut are you using? If it's a pinch lock nut, I use a regular nut to pull the shaft in tight. Than I'll remove it and replace it with the pinch lock toqued to spec.

If it's the original castle nut I'll hit it a couple times with an impact gun (as suggested above). Just need to pull the pin in tight enough to not spin.