Installing ball transfer units into a trackball

[deama]

Hi, so I'm not sure if this is the right place to post, I just want some help on how to do this, or just some advice:

I have an elecom huge trackball and haven't been entirely satisfied with it's tracking (how the ball rolls). I went to my local place and asked to test out their trackballs and I noticed that most of them kinda feel the same (Apart from a CST), so I think this issue is due to the static bearings sliding against the ball's surface.
Anyway, I had an idea to replace the bearings with ball transfer units as I've seen it working quite well, here are the types I've ordered: https://www.amazon.co.uk/Meoly-Transfer ... nsfer+unit

Here are some images of my trackball without the ball: https://imgur.com/a/qDU0Ubc
And here are images of a dissassembly guide of an elecom deft pro, not my one, but a very similiar one nevertherless:
https://imgur.com/r/Trackballs/XzUOey1

Right, so, my idea is to basically remove the artificial ruby bearings that you can see, and puncture 2 13mm holes through the 2 layers of casing. I will then create a 13mm hole that will go through the first layer, this hole will be located close to the optical sensor (roughly where the ruby bearing is at); I will put the transfer units inside of these holes. The idea is that I will use the 2 13mm holes from earlier and adjust how much of a distance I need it to be to hold the ball effectively, because if I just put them where the current ruby bearings are, my current ball will be way to big for that. An alternative could be to just get a smaller ball, but these optical sensors were designed to work with specific ball types, so I am not entirely sure which balls will work.
My plan is to use a soldering iron to make these holes as a drill would be too big and clumsy for me to drill through, although I am not sure about this (any advice about this?). I think the plastic used for the mouse is some sort of ABS?