Grinding gears is never a good thing. You can either replace the entire gearbox or take it apart and replace one or two gears. The first option is much more costly but it's a much easier repair. Not sure if the issue you're having is something that's within your scope of abilities? Give our friendly parts staff a call and we'll do our best to see which gear you need for your mower.
Not sure which gears & gearboxes are used on your model? Use our online parts manuals to double check!Parts Manuals