Hello, Steve.
First, you'll need to check the ballscrew isn't floating in the bearings and the locknut is tight.
If you still have the clunking, it is probably overcomped in the X-axis minus map. Go to the toolchanger diagnostics page and press enter 642 enter.
Select the X-axis minus map, press enter backlash comp and enter the amount of you kick as a minus figure. save, exit and re-check.