I purchased a secondhand Montblanc Classic Black GT, and the seller provided me the information that there is a small resin crack inside.
This may not harm the mechanism itself, though I personally don’t like cracks…
This reminds me of a similar component I have in my Tombow Mano BP — it also has cracks in the resin, which I simply cured by wrapping a tight piece of tape around the whole plastic element, but without any overlapping with the metal parts, because from what I can understand, it just enforces the twistaction deployment of the pen tip / lead feed via some sort of friction-based action. It is a delicate component, but the tape seemed to fully restore its inner workings.
Also, from what I can see, it might be a piece available as well by some parts manufacturers; I thought I had seen something similar in the SCMIDT catalogue, but upon double check the design of the pieces seems different.
I still think this is a relatively common and replaceable part, but I do not have an immediate reference to help. I’ll try dig a bit deeper, maybe something pops up…
