[Christine88]

If hobby level, recommend eBay for used linear guides such as THK, NSK, IKO, Hiwin, Rexroth and others. Don't count on any direct drop-in replacement, more like building a new machine using what you can from the old.

Depending on materials you are cutting and the accuracy you are hoping for, you may need to look at rigidity as well. Then look at the spindle, tool holders, etc. Not knowing exactly what Inventables Kit you are dealing with, your components for linear drive may need to change as well, e.g. does your mill currently use precision ground ballscrews, rolled ballscrews, rack and pinion, or belt drive.

But if it is all in the name of fun, incremental improvements and learning are a great way to go.

Thank you for replying. No there is nothing precision ground at all. It uses delrin v-wheels that ride on like shaped rails that are an integral part of the makerslide aluminum extrusion.