[www.mcmaster.com] :
Or maybe an L-shaped hex key. These are pretty cheap, too, and you can get them anywhere. [www.mcmaster.com] :
Edit: Unless I'm mistaken, there's no significant need for this shaft to be completely round -- it's not intended to move often.

Or maybe an L-shaped hex key. These are pretty cheap, too, and you can get them anywhere. [www.mcmaster.com] :

Edit: Unless I'm mistaken, there's no significant need for this shaft to be completely round -- it's not intended to move often.