Hedge cutter blades wear in several places on the cutting tooth profile, the only way to ensure a quality re grind is for the blades to be removed from the machine, stripped down and cleaned. Then ground to the correct angle again. Over the years I have mastered this process in order to achieve a grind equal to new.
There are obviously times when blades have gone passed the point of being made perfect again, in these situations, I will give customers the option for blade replacement or grind best as poss.
All blades are ground on my own designed and built grinding machine.