Working logically from the head-stock outwards, it’s could be the Morse drive on the head-stock is running off centre – so,remove the spindle and check that the insides of the taper run true and centred…. no debris inside etc..
If it’s out, check the bearings for side-play. I don’t know if the bearings are adjustable on this lathe or sealed.

Otherwise substitute the drive spindle and spot any difference…..
Good luck..