Okay, if we are going to be technical then...

The blade has a correct way to go on and a not-so-correct way... That hole in the blade has to match up with the bottom of the crank correctly or it's gonna hit the deck housing...

There may have been a washer between the crank and the blade... Yeah, I know there is one under the blade but...

Here's what you do... Rotate the blade 360 degrees and see what's what... if the crank is bent (which I doubt) then you will see that in the way the blade moves...

I am betting that you just bent a blade and have not installed the new one correctly...

B~