Whoever last used the bandsaw and put the 1/2 blade on it: it wasn't adjusted for the blade AT ALL. Any time you changer the blade, you MUST adjust the blade tracking, tension, upper guides, lower guides, upper bearing, and lower bearing. If you don't know how, ask for help or to be taught. If you don't know how and can't get help, DON'T CHANGE THE BLADE, wait till someone can help you. Swapping blades without doing the adjuments WILL ruin the blade and can damage the saw