How to Replace a Belt on a Lawn Boy L21ZSNC

The Lawn-Boy L21ZSN and Lawn-Boy L21ZSNC both utilize a front drive self-propelled transmission system to help the user of the mower navigate his yard. This allows you to guide the mower instead of pushing it. The mower uses a small drive belt that takes energy from the main shaft of the engine and transfers it to the transmission. As the belt ages, it stretches and eventually the mower stops propelling forward. Correct this by changing the belt.

Screwdriver

Instructions

- 1
  Locate the transmission cover. It is a black box that protrudes upward from the mower deck. Remove the screws that hold the cover onto the deck with a screwdriver and then remove the cover from the deck.
- 2
  Grip the belt with one hand and turn the setscrew located next to the pulley on the transmission with a screwdriver until the belt is loose enough to pull from the pulley.
- 3
  Place the Lawn-Boy L21ZSNC on its side so the air cleaner faces upward.
- 4
  Pull the loose belt off the pulley located on the mainshaft of the engine and then discard the belt.
- 5
  Place the new belt onto the pulley and then stretch the belt though the small hole in the mower deck that allows access to the transmission.
- 6
  Place the belt on the transmission and hold it in place. Tighten the screw until the belt is tight.
- 7
  Place the cover onto the top of the Lawn-Boy L21ZSNC mower deck and secure it with the screws.

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