Whirlpool wtw4815ew1 Black Residue/Marks and Shaking Violently

Hi

Have a top load wtw4815ew1.

Quite a while back, I started getting black marks on clothing. After about 3 or 4 more washes, the washer would shake violently when in spin cycle.

Shocks seem fine. I out the washer on its back, and can hear residue moving around (not just water). In addition, I can see black chips on the bottom of (want I think is) the outer drum.

Any ideas?

Thank you.