Thanks BigPoppa!

After re-reading my questions, I think the question I meant to ask is: Whether it sounds like a pulley bearing failure is the cause?

The guy asked my sister about the racket the pulley was making before it failed. But, as she told him, she says there wasn't any noise until right before the failure (immediately before).

In other words, the way the shop has handled it, it seems like they are trying to come up with a plausible cause for which they aren't responsible (since it's going to be major work). However, this shop has a good rep and maybe this engine has bad juju.