X axis drive

[Doddy]

Just to re-iterate Sterob's recommendation - the 3040's and similar out of China are not a single design - so there's no easy answer to your question than to measure and search for a suitable replacement.

If you've not played with a ball screw before, be aware that you're probably better to getting the nut as well - and that removing the nut must be done with care if you're not going to lose any bearings in the process (e.g. if you need to swap the orientation of the nut) - google that for more info. Also, when you say "complete replacement" - just what do you mean by "complete"?, screw?, screw+nut?, screw+nut+bearing-blocks? etc. I guess the screw+nut, but it's unclear from your post.

If you post a good picture of your screw we might be able to identify it. Common size for a ball screw would be 1605 (16mm diameter, 5mm pitch) then you just need to specify the lengths of the machined ends. But many of the cheaper 3040s are on trapezoidal/acme threads, rather than ball screws.