You did have the pan off when changing belt so you could see everything? The new belt is right one compared to the worn one? Parts people can screw up. Craftsman 24 could’ve been made by a number of different manufacturers. Model number is a must to identify what belt you need. Folks run into this issue all the time. The only way to be sure about belt size is with a belt measurement tool that many vendors have. Yes, recheck everything as the belt might be on the wrong side of a guide or some such.