Realign the belt into its proper position.

Place the belt in between your 15 mm socket and the tensioner.

Turn the tensioner to the right to relieve the tension and place the belt back on.

Once you have done this, release the pressure you are applying to the tensioner and make sure that the belt is properly aligned.

Use caution when placing the belt back on. Do not release the tensioner until you have aligned the belt or you could pinch your finger.