Took another look. There is nothing I can see that
would indicate something went through it. Gear
teeth have some rust pitting but are intact. No
discoloration to indicate it got hot at any time.
The gear case had been drained but remaining
water droplets would indicate it was leaking.
The black lines on the gear case is where the
bearing is located in the gear case. I can’t detect
any bulging or cracks inside or out. If I hold the
race together in still spins well (Video). The
bearing felt really good when it was in the
gear case and was the reason I took it out to
use in a better looking gear case. If I had intended
to use that gear case I never would have known
it was broken. To have just enough water in just
the right place to brake the race and not do any
other damage would be unlikely yet it seems to
be the best explanation. I guess it shows you
should take the time to check everything rather
than assume something is still good.
https://www.youtube.com/watch?v=LI5ahmdupjc
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.