Hi Joe,
The rear bearing cage failure is common on the TT 40/46. When I get a new engine, I replace the rear bearing with a Boca Polymite plastic cage bearing.
http://www.bocabearings.com/
The standard steel cage rear bearing that comes in the TT 40/46 doesn’t hold up in a racing application.

The blown glow plug is a consequential damage from the cage failure.

Bill