Important: When it comes time to adjust or tension the belt, be very careful to not “over tighten” the belt. You should only adjust the belt in 1/4 turn increments. Also, if you need to align the belt from left to right, always adjust the left side bolt only. The simple rule of thumb for aligning the belt is this: working from the (user) left side bolt, if you need to move the belt to the right, “tighten” the bolt (turn to the right in 1/4 turns only). This will move the belt slightly to the right. If you need to align the belt to the left, “loosen” the left side bolt (turn the bolt to the left in 1/4 turns only). This will move the belt to the left. Anytime you need to either tighten the belt or align the belt, you should have the treadmill running at around 3.0 mph. Also, these adjustments can take up to 30 seconds to affect the position of the belt so please be patient. Most of this information is in the owner’s manual and if you should have any questions, please do not hesitate to call us.