Z wobble was horrible on my CTC i3 (you'll see it in the photos I've uploaded).

I saw Jimmy's video on YouTube (https://www.youtube.com/watch?v=zx8fhBA4JwY) and found the part but it needed to be level for my printer so redesigned it slightly to suit.

I printed a new benchy and did the comparison photo in the files and although there are still other artefacts and issues to solve, the Z wobble was much improved!

Simply place an M8 nut in each part, remove the x axis and then the lead screw nut from the printed parts. Place the new parts onto the threaded rod and then seat the X carriage, minus the removed lead screw nuts on top of the new printed parts. Make sure the X carriage is square to the bed and level and print!