Product review (5 stars): Solved the metal grinding noise coming from my Kenmore dishwasher.
My Ken ore Elite was becoming quite noisy (metal grinding sounds) and when I took it apart the chopper blade looked normal.  But I ordered a replacement just the same since it isn't an expensive part and the simple swap of the parts completely eliminated the excessive grinding noise.  You can find videos online to disassemble your dishwasher and the whole repair job is less than 20 minutes.