My router was having some slippage problems, on Z axis, due to the weight of the spindle and some wear on the ball screw assembly.

Hence I decided to buy a new screw assembly, and had to lathe it to size to fit the original fixture.

I also had to chanfer it, in order to provide a key lock, that prevents slippage between the axel and the motor.

I still have some extra changes that need to be made, since the new ball bearing fixture is larger than the original one. So, some more hacking to come in the near future.