How long did those stones get used without clean off?????

Try freshening up the stones surface with some fresh sand paper, say 80 grit or so.

Then use water with Dawn and scrub with a toothbrush. Once clean keep clean from blade to blade.

I would not use WD40 unless I was going to stay with oil. Otherwise stay with water and clean stones.

"The significant problems we face cannot be solved at the same level of thinking we were at when we created them."
Albert Einstein

At Khe Sanh a sign read "For those who fight for it, life has a flavor the protected never knew".