Y Axis Backing Plate Upgrade

I got the original Handibot, i check the website and discover this upgrade "Handibot v1.1 Y Axis Backing Plate Upgrade".

So im asking, for what is this for? Can i upgrade it myself ? Another Question i have , my limit sensor are not working any more,
where can i buy them?

The backing plate upgrade kit includes the screws, wrenches and drill bit necessary for any Handibot user to perform the upgrade. It will take about 30 minutes to perform and you can find the instructions here: [shopbot.dozuki.com]

The kit was created to allow for easier re-alignment of your tool based on the procedure documented here: [shopbot.dozuki.com] We found that alignment could sometimes be difficult when the screws became seated in the plastic of the handibot frame. The backing plates provide a better surface on which the screws can clamp the handibot frame to the bearing blocks. This kind of precise alignment is only really necessary for users that are interested in tiling large files (using the large material indexing jig).