I want to share my method for truing a lathe chuck. At least I haven't seen it used. There are several fixtures you can make to preload the jaws. I simply glued them with hot melt glue. Very easy to remove afterwards. Not much resistance when I tightened up the chuck to take in the play. Maybe there is not important to have normal working tension on the jaws when doing this? I managed to reduce the run out from 0,07mm to 0,01mm (aprox. 3 to 0.4 thou).