Get a blade balancer to make sure you're taking off appropriate amounts on both ends.
I had one quite a few years ago, where I started lobbing off bits on the back of the blade on one side to get it balanced. I don't know if it was a bad forge or extra gunk stuck to it at manufacturing, but I had to sit and grind bit after bit to level it out.
It's part of a lawnmower blade balancer. It's missing the bottom half.
Blade balancer is even cheaper - $5 on Amazon or Home Depot.
https://www.amazon.com/dp/B000VYFOJM/
It is on amazon too if you prefer them...
https://www.amazon.com/Oregon-Mower-Blade-Balancer-42-100/dp/B000VYFOJM