Park the Husqvarna lawnmower on a level working surface. Push the brake pedal in while engaging the parking brake. Pull down on the clutch handle to move it into the "Disengaged" setting.
Slide the key to the "Off" setting on the ignition and pull it out. Disconnect the rubber boot of the spark plug wire from the end of the plug. Position the plug wire so it won't contact the spark plug during maintenance.
Push down on the attachment lift lever to lower the mower deck to its lowest position. Roll the drive belt slowly off the rear drive pulley and out of the belt keepers just in front of the pulley. Pull the retainer spring out of the anti-sway bar on the chassis. Push the housing guide out of the bracket.
Unhook the clutch cable spring from the idler arm. Pull the retainer spring out of the front link assembly and disconnect the front link from the mower. Disconnect the suspension arms, pulling the retainer spring out of the brackets. Pull the retainer spring out of the rear lift links and disconnect them from the rear brackets.
Pull the mower deck out from underneath the Husqvarna lawnmower. Roll the mandrel pulleys with your hand while pulling the drive belt off the pulleys. Remove the belt from the idler pulleys. Pull the belt out of the mower deck.
Work the new belt into place on the two mandrel pulleys and into the belt guides. Wrap the belt around the two idler pulleys. Position the belt into all the guides. Reinstall the mower deck in the reverse order of its removal. Reconnect the drive belt to the rear drive pulley.