[Fiddlebog]

My guess is that the punch has significance if it is lined up to other components. I.E.: you could tell the orientation of other components without seeing them.
Just a guess.
BYprodriver could be right about it being an artifact of manufacturing, though (although seemingly being confused about the component in question).
Having worked in a machine shop, I've put marks in seemingly odd places, either for our use, or to help with assembly in some way.
The way these engines were manufactured in the original facility could have had an important use for that mark. German sophistication often goes much deeper than what is apparent at surface level.

Ultimately, though, I do not think the orientation of the IMS is functionally significant, as it appears to be radially symmetric other than the mark.