When a rep is struggling in sales, take time to have a conversation with them. Ask them to go home over the weekend and think of 1) what three areas they need to improve the most and would make the biggest difference, 2) what are they going to do about it, and 3) what do they want your help with. They need to step it up. You can't want it more for them than they do for themselves. Then it's your job to teach them and show them the way on what they need your help from. You can't give up on someone until you take the time to teach them. After all it's the right thing to do and it models the way for others.