Denford Starmill - how to remove spindle drive belt?

[Fgc]

Dear all

I am in the process of refreshing my Starmill by gutting all electronics and replacing belts.

I have not been able to remove the spindle drive belt because it is trapped by the Z-Axis leadscrew as per photo below.


View from the top. for the life of me, i cannot see how this castellated nut is holding the leadscrew in since it is locked unto the leadscrew itself. I am tempted to undo the nut to see what happens but at the same time i am reluctant since it appears that this might be pre-loaded and i do not know how much the pre-load is when i reassemble it.


Appreciate your help and advise.

Kind regards
francis