Throwing pulley/alternator belt

I would buy a new belt and try it, once a belt flies off, they get crooked.
I’ve been through several belts. Of different sizes. They all get tossed in the high rpm band. I’m certain it’s walking off since the alignment is offset, albeit by very little.

** Ah, I see what you’re saying. Get a new belt when I get it straightened out cuz any tossed belt has been compromised. Thanks!