Hi Alex, thanks for your comment and kind words.
I agree that feedback is vital, both ways and for the team and leader as well.
Coaching or mentoring a team member can be such a rewarding (and frustrating) process however it's a leaders responsibility to get the best from the team; we can't always fire them and move on. Of course, we need to have a point of no return also, which you have clearly set. There's always going to fliers and crash-and-burners and the latter need to be addressed as sometimes they can be lifted and sometimes they will simply weigh down the team, as you say above. The team will perform at the level of the weakest link and whist there's times and situations that's possibly acceptable, I've preferred to have the less-capable operators rise to the others rather than the other way around.
I get the feeling you're well-equipped and up to the task and I wish you all the best...If you like, drop me a line to let me know if you achieved mission success.