Manufacturing marks or wear?

[Duncan Grimmond]

Given that the scars are all almost identical in a slightly asymmetrical scallop form I'd guess that the same mistake has occurred at the same moment of each spline machining process. The marks appear to have been made by perhaps three different cutters or the same cutter at three different settings. Without having the object in my hands that is as far as my forensics will take me.
I'm sure a regular machinist could be more specific if he had the item in hand and a good magnifying glass for closer inspection.
Could it be that someone "liberated" a factory part prior to machining and did it himself at home?
But why?

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As the scars are virtually identical and form an asymmetrical scallop shape in line with each spline I think they must have been formed by a repeated operator error or a malfunction of machine repetition.
Having the thing in your hand with a good magnifying glass would help with the forensics.
Could an unmachined part have been "liberated" and finished at home? Why?

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Don't know what happened ther.. I posted, the post vanished, I rewrote and reposted, both appear. Could the machinist have had the same problem 80 years ago and has come back to haunt me?