This may be a case of stupid owner tricks, but I have managed to break my motor twice in the last year or so (most recently today).
To reproduce (in preparation for emptying the basket):
1. Shut off pump (by going into service mode)
2. Turn on the pump after waiting a few seconds (to let the heater cool down while I brush out the basket that is going in).
3. Hear an awful gurgling/priming sound followed by a large pop/crack
It appears that the motor has tried to unscrew itself from the impeller, ramming the impeller into the housing and putting sufficient force (not torque) on the shaft that the back of the motor housing breaks. It looks as if someone had taken a hammer to the impeller trying to knock the shaft out the backside of the motor.
The first time I had attributed it to a build up of DE in the impeller housing causing the impeller to get stuck. Today, the only thing I can think of is that maybe I didn't wait long enough for the water to stop moving around before starting the pump again.
In any event, part of the housing has detached as well.
I think I will be ordering a new motor and impeller assembly tomorrow. Has anyone seen this happen before? How can I avoid it in the future?
The motor is an AO Smith Centurion B130, 2 HP uprated to 2.4. The pump housing is a Jandy JHPU2.5. This particular motor is less than a year old.