It sounds to me like you have a LOT of ways to leverage the behavior that you want out of him.
I'm not sure what you're asking for-- is it to provide leverage to get a spark of internal motivation firing?
I'm not sure that you CAN do that externally.
I'm also going to throw out another idea-- my DD has no particular problems with school... but it can sure feel like an ordeal to all of us. She drags her feet and underperforms with some regularity.
Why?
Because learning makes her feel inadequate and insecure.
That's her perfectionism talking, by the way. I don't suppose that your son found that years K-4 (or so?) were mostly about 'showing what I know' rather than "learning what I don't" by any chance?
My DD had concluded LONG before middle school that school was the place where you "got rewarded for already knowing the answers."
She's never liked writing because it requires effort and the outcome is not so clear-- she prefers things where the outcome is graded. That way she can be "perfect."
{rubs temples} This is NOT NOT NOT a good thing. She hates learning. It makes her feel stupid. She loves knowing because that makes her feel smart.
Honestly, I'd use the leverage that you have with sports eligibility and just keep talking to him (and listening to him) re: his motivational struggles with school.
Make sure that he understands that it IS EXPECTED that he make mistakes, and that this is how you know he is LEARNING. Yes, most kids already know this lesson-- but mine sure didn't by middle school.
