When the blade and the anvil-blade no longer cross, or when the blade is badly damaged, it is advisable to change it.
Regulate the working of the blade and anvil-blade by adjusting the tightening of the nut. The blade should rub against the anvil-blade o
Changing the thumb catch
When the thumb catch is damaged and loosens when used, even when the screw is readjusted, change it.