Step One
Remove the top cover from the mower this may vary depending on your model. Next remove the main cowling with the starter. There is most often 3 bolts holding this part to the mower engine.

Step Two
Once the cowling has been removed and the flywheel is accessible you will need to secure the flywheel with the holder and undo the 24mm nut in the center of the flywheel.

Step Three
Now the nut has been removed you need to gently pry up the flywheel. Gentle pressure from different angles will usually loosen it up enough to be lifted off.

Step Four
Once removed you can inspect your flywheel key for damage. and then replace the key with a new one.

Step Five
Once the new key is fitted reassemble in reverse and hopefully your mower will now be up and running.