At some point, if there are no blockages, nothing wrong with the oiling system and no electronic problem, the likely culprit if the gear itself. I suppose if you took the gear off and apart it may hold some clues, but the odds aer it will look just fine.
Unfortunately you won't really be able to tell until you replace the parts, put the engine back together and put it back in the car.
BTW, what kind of oil were you using when this all happened? and what OCI?
I hope you sort it out soon.