Remove the hand wheel from the x slide leadscrew, don't lose the key!
Remove the spindle support bracket, 2 x M6 cap heads......The x slide should then slide toward you, with the cover....You could at this point unscrew the lead screw leaving the nut attached to the casting. You should the see why the nut is stuck, it is retained with a csk screw and there should be a socket head grub screw in there too....the actual nut has a shoulder on it that fits into the underside of the cross slide, there's insufficient lateral movement to remove it but you'll see how it all comes apart.......I think that's about it...
HTH.....
