Position your Murray mower onto level ground, disengage the PTO lever that turns the mower blades on /off and then set the parking brake. Turn the mower off and remove the key.
Lower the height adjustment lever to the lowest notch to increase the distance between the deck and bottom of the lawn tractor.
Locate the PTO pulley mounted to the bottom of the motor by positioning yourself in front of the mower and then by looking under the mower. Grip the belt with both hands and then pull it off the PTO pulley.
Draw a diagram or make a mental note of the belt routing on the mower deck. If you do not route it incorrectly, the blades could spin backwards.
Pull the belt off the deck's spindle and idler pulleys and then place the new belt onto the spindle and idler pulleys.
Stretch the belt to the front of the lawn tractor and with both hands, slide the belt over the PTO pulley.