I've had a few guys like that, but not as bad. I've sat them down in front of PCATD or some sort of fixed based sim with similar controls to the airplane being used, or even in the airplane without them moving things, and had them set up go through the maneuvers. Sorta like a "write _____ 100 times on the chalkboard" deal. When it seemed like they got the hang of it, I'd assign them a wind direction and walked away and told them to repeat every maneuver 10 times (including clearing turns) and when they were done to come grab me so I can evaluate. It's helped and might be a suggestion for your situation. This is the bad side of instructing, watching someone trying to go for their dreams, you know they have potential, but aren't living up to it and no matter what you do, they just don't get it.