VEVOR E490T Manual Del Usuario página 155

 Blade adjustment
The blade has 4 sides, each side can be used twice and can be recycled 8
times. If the blade is too deep, it is necessary to adjust or replace the blade;
replace the blade, there are semicircular concave holes on both sides of
the blade and use a screwdriver to insert and pry out the blade.
Note: When replacing the blade, some adjustments to the blade itself are
necessary. If the blade protrudes too deeply, it can not only damage the
blade holder but also accelerate blade wear.