Z421 Blade keeps gettin loose

[brim0628]

Have a Kubota Z421 mower. Seems to be a nice unit other than the blades seem to not wanna stay tight. Would this issue be mainly caused by the 2 washers that hold the blades in place or something else?

Thanks for any assistance

 

[Peter 315]

Yes that seems to be a common problem, Yes new washers fix it unless you have a bent spindle/bad vibration .......

 

[RickB]

Put the concave side of the washers towards the blade.