The armor is prone to cracking in certain areas, e.g. the chest or butt plate, where there is a lot of movements and stress.
There are many different ways of repairing such cracks, some people use a t-shirt superglued to the back of the armor and then fill the crack, head on over to whitearmor.net to find out more, that is the stormtrooper detachment.
I personally use leftover scrap ABS from trimming, cut into little pieces and then put into a jar with acetone: the little pieces will melt in the acetone and you will finally have a paste of ABS. I then use this to back up the crack from the inside by gluing a larger solid piece of ABS on with that ABS paste and I finally fill in the crack from the outside, then you just sand it smooth again.
Now if you buy a complete commission, you won´t have any leftovers from trimming which means you would have to ask RS to send you the leftovers too.