Thanks. Yeah, it's a pretty small diameter bolt. I've used those "broken bolt" removers in the past. A few times with success, a few other times where things got worse. Kinda worried about trying to drill into it and get in the exact center when it's pretty difficult to get at it from above and ensure that you are not only in the exact center but also going straight down.
We are going to try JB Weld for now. We found a couple of small washers to contain the weld and keep the broken top piece sitting level. He said it broke without being tight so maybe, just maybe, there will be enough bite to unscrew it. Chances are slim, but we'll see what happens.
