When it works, I actually like the bell, which is weird, because usually stuff like that annoys me; I just find it nice to be able to address all my comments (and see likes) in one place, rather than having to go back and forth between my email and the site. I even went into my settings and turned off the option to get comment notifications by email--have you looked there to make sure that you are set up to get them via email still? (I assume yes, since you're so far into troubleshooting, but since I was just editing those settings it came to mind.)