linear bearing maintenance

When i leaked a few ball bearings from the carriage of a Chinese import HGR15 style linear rail i couldn't find many useful resources on exactly how to fix them. Since i have a brain like a sieve i thought i'd leave some notes here. Maybe they'll help someone else too. I presume the process will be similar for HGR20 and larger rails too. Apologies for the poor camera work; Blame holding a phone while fiddling with bearings. I think you can see what's going on though. Although the size of my rail is 15mm, the bearings themselves are imperial sizes. I need to order 1/8 inch for these. Note that with a fully populated carriage there is still a small amount of space in each race. It would be possible to install one extra ball without realising. These are the exact rails: https://www.aliexpress.com/item/10000330734443.html