BESS 10

[tailmotor]

I've talked to the manufacturer about it. Personally, I think it depends on how he holds the knife blade when he grinds. If he holds the blade so that the pressure increases towards the ends, the middle is almost not ground. Alternatively, the knife has a slight skew that appears at this grinding level.
Maybe someone else has any idea? It may seem a bit disturbing with this great variation on this short blade.