yep, I've seen issues with that area on a 31 too. One case the center gear slipped off the shaft. Others had one of the gear teeth broken. Given this area is worked as the rotar spins I'd guess fatigue to the metal. Of course not having enough lubication would speed the issue up as well. There maybe other factors elsewhere.
now in the case of the center gear having slipped off I just tossed the movement into the parts bin. For the others I replace the winding gears and all was fine.
the good thing is that 31's are easy to come by. and I may have an NOS\factory refurb available.