Need help on a Leinen Lathe please

Hello,

My buddy has a Leinen LZ4S lathe that has been a bit too hot.
At least that is what I think...

The spindle in the headstock is turning too heavy after he had turning nylon for hours...
Probably he has not oiled it for ages, has had the lathe for ten years and he never oiled it..
Now you can hardly turn the chuck by hand if it's not connencted.
So I was planning to take out the spindle, but all I can do is release the radial bearing play..
The chuck will not come loose, so I can't take the spindle in the headstock apart.

My question is simple :rolleyes5:
How do you take the spindle apart and take it out the headstock?
I can't find the info I need on this.
I assume the chuck is turned on with threads, because I don't see any other way the chuck is mounted.
We want to take this machine apart and clean it, measure it and put in new bearings as neccessary.

Is there anybody who has info on how to take the headstock apart??
Any info is welcome.
Thank you in advance!!

The pics:
The first is exactly the one we have, the second is the headstok.
If neccessary I can make mor pics.

Attached Thumbnails