How to Fix an Old Cub Cadet Mower if the Blades Won't Spin

Locate the lift lever on the rear left fender and lower it to the bottom notch.

Remove the screws that hold the belt guards over the two large pulleys on the mower deck. Use a Phillips screwdriver for this. Pull the guards off and place them off to the side.

Look under the front of the mower deck and loosen the bolt that holds the belt keeper over the mainshaft pulley extending from the bottom of the engine. Position the keeper away from the pulley.

Place the drive belt onto the V-groove of the mainshaft pulley and then secure the belt keeper in place. This will hold the belt for you while you install the replacement belt onto the mower deck.

Pull the between the two small pulleys on the mower deck and place the belt over one of the larger pulleys on the deck.

Locate the idler pulley on the mower deck. It is one of the two smaller pulleys located between the two larger pulleys. It has a square hole in the mounting bracket and a spring attached to the mounting bracket.

Place a 3/8-inch ratchet drive into the square hole and then rotate the pulley away from the belt.

Stretch the belt over to the second large pulley and then place the belt over the pulley.

Remove the ratchet driver from the idler pulley to apply tension onto the drive belt.